heteromultimetallic compounds based on polyfunctional … · 2020. 1. 22. · heteromultimetallic...

Heteromultimetallic compounds based on polyfunctional carboxylate linkers

Khairil A. Jantan,†‡ James A. McArdle,† Lorenzo Mognon,† Valentina Fiorini,+ Luke A.

Wilkinson,† Andrew J. P. White,† Stefano Stagni,+ Nicholas J. Long*,† and James D. E. T.

Wilton-Ely*,†

† Department of Chemistry, Imperial College London, Molecular Sciences Research Hub,

White City Campus, London W12 0BZ, UK.

‡ Faculty of Applied Sciences, Universiti Teknologi MARA (UiTM), 40450 Shah Alam, Malaysia.

+ Department of Industrial Chemistry “Toso Montanari” – University of Bologna, Viale del

Risorgimento 4, Bologna 40126, Italy.

e-mail: [email protected]

e-mail: [email protected]

In memory of Professor Robin J. H. Clark FRS, CNZM (1935 – 2018)

Abstract

A series of homo- and hetero-nuclear, bi- and trimetallic compounds are accessible using

polyfunctional linkers with carboxylic acid and alkynyl or pyridyl donor combinations. This

versatile approach affords reaction at a specific donor site in each case, to accommodate both

ruthenium(II) or osmium(II) units and also rhenium and gold centres. Due to the orientation of

the nitrogen donors of the bipyridyl moiety in 2,2’-bipyridine-4,4’-dicarboxylic acid, the metal

addition must be performed in a certain sequence due to steric considerations. One example

was investigated crystallographically to add to the spectroscopic and analytical

characterisation performed for all complexes. Photophysical investigations reveal the effect of

incorporating second or third row transition metal centres. This approach was expanded

through the use of a linker bearing both carboxylic acid and alkynyl functionalities, 1,1’-

ethynylferrocene carboxylic acid. This allows initial coordination of the carboxylate donors to

be followed by the formation of either an acetylide or a vinyl bridge to another metal, providing

access to heterotrimetallic (FeRuOs and FeRuAu) compounds as well as a

heteroheptametallic Fe3Ru2Au2 example. Preliminary electrochemical studies were performed

on the latter example.

Keywords: Multimetallic, ruthenium, osmium, vinyl, carboxylate, gold

Introduction

The utility and versatility of transition metals can often be enhanced by bringing multiple

metal centres into the same assembly. This approach has been employed successfully in many

areas, including catalysis,1 sensing2 and imaging.3 Many multimetallic compounds involve

multiple units of the same metal, such as metal-organic frameworks (MOFs)4 and coordination

polymers,6d,e but increasingly heteromultimetallic systems are being exploited due to the

possibilities afforded by the incorporation of multiple metal-based properties within the same

system. However, the rational synthesis of heteromultimetallic compounds has always proved

a greater challenge due to the requirement to link different metals together in a controllable

manner. This can be achieved through the protection and deprotection of donor groups, but an

attractive, more synthetically straightforward option is to tailor bifunctional linkers to the metals

involved. This approach has been employed by us7 and others8 to prepare molecular assemblies

consisting of 2-6 metals, including compounds with six different metals.9

Due to our interest in 1,1’-dithio ligands,10 our previous contributions have mainly

focused on sulfur ligands and these have proved exceptionally useful in the construction of

both molecular and nanoparticle systems. However, the range of metal units based on

carboxylate chelates is wide and encompasses examples of metals in many different oxidation

states. This is borne out by the widespread use of dicarboxylic acids and bipyridines as

bridging ligands in coordination polymers5 and metal-organic frameworks(MOFs).4 In this

contribution, the reactivity of 2,2’-bipyridine-4,4’-dicarboxylic acid (H2dcbpy) is explored. This

dicarboxylic acid has been used extensively in the preparation of ruthenium-based

photosensitizers, such as [Ru(NCS)2(H2dcbpy)2],11 and its commercial availability is likely to

be driven by this application. However, in such compounds, the presence of the carboxylic

acid groups is simply to aid water-solubility, whereas the work described here uses this

commercial compound as a trifunctional linker for multimetallic assemblies based on rhenium

and group 8 metals. The differing reactivity of nitrogen and oxygen donors allows the stepwise

construction of these heteromultimetallic compounds. This difference in reactivity is also

employed in the other linker used in this contribution, 1,1’-ethynylferrocene carboxylic acid, in

which the carboxylic acid and alkynyl groups display contrasting reactivity profiles (Figure 1).

In order to illustrate the potential for wide-ranging application of this approach, a series

of different metal units were employed, which possess widely employed properties, such as

reliable redox behaviour [of the Fe(II/III) and Ru(II/III) couples] and the photophysical attributes

of Re(I)-diimine moieties.

Figure 1. Carboxylate linkers used in this contribution.

Results and Discussion

The species [Ru(CR=CHR’)Cl(CO)(L)2] (L = PiPr3,12 PPh313) and

[Ru(CR=CHR’)Cl(CO)(BTD)(PPh3)2] (BTD = 2,1,3-benzothiadiazole)14 have been used widely

as versatile entry points to ruthenium vinyl chemistry.15 The latter BTD complexes have since

found application as probes for the chromogenic and fluorogenic sensing of carbon

monoxide.16 Both 5- and 6-coordinate complexes undergo reaction with deprotonated

carboxylic acid ligands to yield the corresponding octahedral carboxylate complexes.6b,6d,6g,17

Such ruthenium complexes also react with bipyridine ligands to yield cationic complexes of

the form [Ru(CR=CHR’)(CO)(bpy)(PPh3)2]+. It was therefore not immediately clear whether

commercially-available 2,2’-bipyridine-4,4’-dicarboxylic acid (H2dcbpy) would react at the

nitrogen or oxygen donors, or both. It is known6b that, unless a base is used, the addition of

carboxylic acids to ruthenium vinyl complexes results in cleavage of the vinyl group. Thus,

H2dcbpy was stirred with excess base (sodium methoxide) before addition of two equivalents

of [Ru(CH=CHC6H4Me-4)Cl(CO)(BTD)(PPh3)2]. After a further 2 hours and subsequent

purification to remove inorganic salts and excess base, [{Ru(CH=CHC6H4Me-

4)(CO)(PPh3)2}2(µ-dcbpy)] (1) was isolated as a brown powder (Scheme 1). 31P{1H} NMR

analysis revealed a singlet at 38.2 ppm confirming clean formation of the new complex as well

as suggesting the mutually trans disposition of the two phosphine ligands at each metal centre.

A carbonyl absorption was noted in the solid-state infrared spectrum at 1928 cm-1, alongside

an absorption assigned to a coordinated carboxylate unit at 1573 cm-1. Both of these features

were found to be at values shifted compared to those in the precursors. The retention of the

vinyl ligands was confirmed by the presence of characteristic resonances in the 1H NMR

spectrum at 5.89 (d, Hβ) and 7.81 (dt, Hα), showing a mutual coupling of 15.2 Hz, while the

lower field resonance also showed 3JHP coupling to the two equivalent phosphorus nuclei. The

presence of the tolyl substituent was also clearly indicated by resonances at 2.23 ppm (s,

CH3), 6.35 and 6.82 ppm, with the latter displaying an AA’BB’ spin system showing a coupling

of 7.8 Hz. The features at 6.92 (dd), 7.66 (m) and 8.46 (d) ppm were assigned to the bipyridyl

unit. In particular, the chemical shift of the 8.46 ppm resonance18 suggests that the bpy unit

remains uncoordinated to the ruthenium centre. The overall composition was confirmed by

mass spectrometry and elemental analysis.

Following a similar strategy, the dark red [{Ru(C(C≡CPh)=CHPh)(CO)(PPh3)2}2(µ-

dcbpy)] (2) was formed from the coordinatively-unsaturated enynyl compound

[Ru(C(C≡CPh)=CHPh)Cl(CO)(PPh3)2] and H2dcbpy in the presence of sodium methoxide

(Scheme 1). In addition to carbonyl (1929 cm-1) and carboxylate (1522 cm-1) absorptions in

the solid-state infrared spectrum, a new band was noted at 2163 cm-1, which was assigned to

an C≡C absorption originating from the enynyl ligand. Other spectroscopic features for 2 were

found to be similar to those observed for 1 apart from a broadened singlet absorption in the

1H NMR spectrum at 5.79 ppm, which was assigned to the Hβ proton of the enynyl ligand.

Scheme 1. Synthetic routes to compounds 1 to 7 (L = PPh3).

In order to better explore the coordination behaviour of the dcbpy ligand, a different

and more robust precursor was employed. While allowing fewer possibilities to tune the

functionality of the ligands, cis-[RuCl2(dppm)2] offers better resistance to acidic conditions than

the vinyl moieties and is less prone to the loss of the phosphine ligands than the

bis(phosphine) complexes. Following a similar procedure to that used for the synthesis of 1

and 2, cis-[RuCl2(dppm)2] was added to a mixture of H2dcbpy, sodium methoxide and NH4PF6,

to yield the complex [{Ru(dppm)2}2(µ-dcbpy)](PF6)2 (3·2PF6) as a dark brown solid. 31P{1H}

NMR spectroscopy revealed a dramatic change in the chemical shift of the two resonances,

from -27.0 and -0.9 ppm (JPP = 36.1 Hz) in the precursor to -11.9 and 8.7 pm (JPP = 38.8 Hz)

for 3·2PF6. The 1H NMR spectrum was dominated by the multiplets arising from the phenyl

protons in the aromatic region, but a singlet at 8.55 ppm and a doublet at 8.91 ppm could be

discerned for the protons of dcbpy. The protons of the PCH2P methylene bridges of the dppm

ligands were found to resonate at 4.16 and 4.76 ppm. The infrared spectra showed an

absorption at 1521 cm-1, attributed to the coordinated carboxylate moiety. The overall

composition was confirmed by mass spectrometry and elemental analysis.

Despite repeated attempts, experiments to obtain single crystals of 1 – 3 suitable for

X-ray analysis proved unsuccessful. However, the charged nature of 3 allowed a range of

different counterions to be investigated in order to improve the crystallinity of the material. The

use of the more bulky tetraphenylborate anion had the desired effect and allowed yellow

needles of the complex [{Ru(dppm)2}2(µ-dcbpy)](BPh4)2 (3·2BPh4) to be obtained by slow

diffusion of diethyl ether in a dichloromethane solution of the compound (Figure 2). Some of

the structural features of the complex match those determined for mononuclear compounds

reported in the literature, such as [Ru(O2CMe)(dppm)2]BPh4.19 The geometry of the molecule

is determined by both the constraints of the three bidentate ligands, all of which coordinate to

the ruthenium creating a four-membered ring, and on the high steric demand of the dppm

ligands, and especially of the phenyl moieties. The influence of the bidentate nature of the

ligands can be seen in the distorted octahedral geometry around the ruthenium atom, and

especially in its angles: the angle O(3)-Ru(1)-O(1) formed by the carboxylate moiety is

59.79(15)°, while the intraligand angles arising from the dppm coordination, P(13)-Ru(1)-P(11)

and P(43)-Ru(1)-P(41), are 71.70(6)° and 72.45(6)° respectively. In order to accommodate

this deviation from the 90° of a regular octahedron, the cis-interligand angles were found to lie

in the range 90.23(11)˚ and 108.41(1)°. It is noteworthy that the axial Ru-P bonds are longer

(2.3361(16) and 2.3570(16) Å) than those trans to the oxygen atoms (2.2640(16) and

1.916(17) Å), probably due to a weak trans effect. Another interesting feature is the difference

in bond length between the two oxygen atoms and the ruthenium: Ru(1)-O(3) is 2.161(4)Å and

Ru(1)-O(1) is 2.232(4), and this asymmetry is likely to be due the steric hindrance of the dppm

ligand. The rest of the bond distances are unremarkable. The entire

RuO2C(NC5H3C5H3N)CO2Ru unit is almost coplanar with very little rotation observed about

the C(6)-C(6A) bond.

Figure 2. The structure of the Ci-symmetric complex present in the crystal of 3·2BPh4.

Since the report by Schulten in 1939 on the discovery of pentacarbonyl halides by the

action of carbon monoxide on the corresponding hexahalogenorhenates,20 these complexes

have been used as synthons for a vast range of substitution reactions, and especially with

diamine donors, such as bipyridine and phenanthrene derivatives. Thus, compounds 1 - 3

were treated with pentacarbonylchlororhenium(I), with the objective of coordinating the

rhenium to the nitrogen donors of the dcbpy ligand. However, despite forcing conditions being

employed (toluene reflux), no trimetallic product could be obtained. The structure of 3·2BPh4

(Figure 1) shows the typical arrangement for the bipyridine nitrogen donors on opposite sides

of the dcbpy ligand. Thus, bidentate coordination of the Re(I) centre would require rotation

about the C(6)-C(6A) bond. In order to probe whether the bulk of the ruthenium termini is

preventing rotation and hence attachment of the rhenium unit or if the coordination ‘pocket’ is

simply too small to accommodate the metal, a different strategy was therefore devised to

obtain the trimetallic compounds. This involved the synthesis of the known orange complex,

[ReCl(CO)3(µ-H2dcbpy)] (4),21 as the starting point for the addition of the termini. Solutions of

4 were thus treated with sodium methoxide and two equivalents of either [Ru(CH=CHC6H4Me-

4)Cl(CO)(BTD)(PPh3)2] or [Ru(C(C≡CPh)=CHPh)Cl(CO)(PPh3)2], to give

[{Ru(CH=CHC6H4Me-4)(CO)(PPh3)2}2(µ-dcbpy)ReCl(CO)3] (5)

or[{Ru(C(C≡CPh)=CHPh)(CO)(PPh3)2}2(µ-dcbpy)ReCl(CO)3] (6), respectively. The 31P{1H}

spectra for both complexes failed to show any significant differences compared to their

bimetallic counterparts (1 and 2), suggesting a very similar environment for the termini.

However, solid-state infrared spectra showed the presence of diagnostic peaks for the

tricarbonyl-rhenium unit around 2019 and 1890 cm-1 while the absorption for the carbonyl

ligand coordinated to the ruthenium was shifted to 1918 (5) and 1919 cm-1 (6). Modest

changes were also apparent in the chemical shifts of the bipyridyl features in the 1H NMR

spectrum of Ru2Re complex 5 (7.01, 7.26, 8.68 ppm), compared to the corresponding

resonances in the compound 1 (6.92, 7.66 and 8.46 ppm) without coordination at the bpy unit.

Mass spectral data and elemental analysis confirmed the hypothesised composition. In order

to complete the series of trimetallic complexes, [{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2 (7)

was obtained from the reaction of 4 with two equivalents of cis-[RuCl2(dppm)2]. The conversion

of the mononuclear complex [ReCl(CO)3(µ-H2dcbpy)], (4) into the trimetallic assembly

[{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2 (7) was also monitored by investigating the variation

of the UV-vis absorption and emission properties.

Figure 3. Absorption profiles of [ReCl(CO)3(µ-H2dcbpy)], (4), red dashed trace and

[{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2 (7), blue solid trace, obtained from ca. 10-5 M

acetonitrile solutions.

The absorption profile of the neutral species [ReCl(CO)3(µ-H2dcbpy)] (4), obtained

from the corresponding diluted (ca. 10-5 M) acetonitrile solution, displayed typical features for

this class of d6 metal complexes, with intense ligand centred (LC) –* transitions occurring

in the 250–350 nm region followed by weaker metal to ligand charge transfer (MLCT) bands

above 350 nm. The coordination of two {Ru(dppm)2} fragments through the deprotonated

carboxylic acid termini of complex 4 provided the dicationic, trimetallic complex

[{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2 (7). The addition of the metal units induced a shift to

higher energy for the MLCT absorption band (max = ca. 365 nm, see Figure 3 and Table 1).

However, the broad profile of this band did not permit the Re(I)-centred transitions to be

distinguished from those arising from the Ru(II) metal centres.

Figure 4. Emission profiles of air-equilibrated solutions (10-5 M in CH3CN, 298K) of

[ReCl(CO)3(µ-H2dcbpy)], (4), red dashed trace, and [{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2

(7), blue solid trace.

In good agreement with the data reported in the literature,22 the excitation of the MLCT

features of a dilute (10-5 M) acetonitrile solution of the complex [ReCl(CO)3(µ-H2dcbpy)] (4)

produced a weak emission centred at ca. 720 nm (Figure 4 and Table 1). The broad and

structureless shape of the corresponding emission profile suggested a metal to ligand charge

transfer (MLCT) character of the emissive excited states,23 and this assignment was further

corroborated by the pronounced rigidochromic blue shift of the emission maximum observed

on moving from room temperature to 77 K (Table 1).24 In addition, the slight but observable

increase of the emission intensity and the concomitant elongation of the emission lifetimes

(Table 1 and Figure S3-2 in the Supporting Information) that were detected upon the removal

of dissolved O2 (i.e. by degassing the acetonitrile solution of the complex under argon)

provided an indication of the triplet spin multiplicity of emissive excited states. If compared to

the neutral precursor species, [ReCl(CO)3(µ-H2dcbpy)] (4), under the same experimental

conditions (10-5 M solution in acetonitrile at 298 K), the dicationic, trimetallic complex

[{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2 (7), displayed a significantly blue shifted (max = ca.

80 nm, see Figure 4 and Table 1), brighter, and longer-lived phosphorescence. This is likely

to originate from 3MLCT excited states, as suggested by the sensitivity of the excited state

lifetime τ and quantum yield Φ to the presence of dissolved O2 (Table 1 and Figure S3-4 in

the Supporting Information). Taken together, these data reveal an effective enhancement of

the luminescent behaviour on going from the neutral complex [ReCl(CO)3(µ-H2dcbpy)] (4) to

the dicationic complex [{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2 (7). The increase in the

values of τ and Φ on coordination of two Ru(dppm)2 units could be rationalised by the increase

of the relative energy of the 3MLCT excited state, as predicted by the energy gap law. Even

though it was not possible to selectively excite the MLCT features of the Re(I) or the Ru(II)

centres, it is likely that the phosphorescent emission of [{Ru(dppm)2}2(µ-

dcbpy)ReCl(CO)3](PF6)2 (7) can be traced solely to the fac-[Re(CO)3(µ-dcbpy)] fragment of

the molecule - an assignment that was supported by the non-emissive character of the

Ru(dppm)2 metal fragments.

Table 1. Relevant photophysical data for compounds 4 and 7.

Complex

(in CH3CN)

Absorption

λabs (nm)

(10-4ε)(M-1cm-1)

Emission 298 Ka Emission 77Kb

λ em

(nm)

τ air

(μs)

τ Ar

(μs)

φair+

(%)

φAr+

(%)

λ em

(nm)

τ

(μs)

4 240 (7.11), 309 (4.05), 400 (0.98) 720 0.012 0.015 <1% <1% 584 2.86(34%)

8.86(66%)

7 243 (11.87), 304 (2.03), 366 (0.88) 638 0.054 0.067 <1% 1.22 594 6.75

a Air = air equilibrated solutions, Ar = deoxygenated solutions under argon atmosphere; + [Ru(bpy)3]Cl2 / H2O was

used as reference for quantum yield determinations (Φr = 0.028); b in frozen solvent matrix, CH3OH.

While compounds 5 – 7 demonstrate the possibility of inserting a metal (Re) within the

polyfunctional linker, the peerless synthetic versatility of ferrocene among organometallic

sandwich complexes offers the option to design a carboxylate linker based around the

bis(cyclopentadienyl)iron(II) unit. This has been explored through the use of 1,1’-

ferrocenedicarboxylate as a linker,25 however, this only provides access to symmetrical

multimetallic compounds. The synthesis of 1,1’-ethynylferrocene carboxylic acid was first

reported in 200926 and this bifunctional molecule was chosen to broaden the approach

described here through the particular and selective reactivity of the ethynyl unit. It was

anticipated that reaction would first take place at the carboxylate donors with the ruthenium

compounds used as precursors above.

Reaction of the 5-coordinate enynyl complex, [Ru{C(C≡CPh)=CHPh}Cl(CO)(PPh3)2],

with deprotonated 1,1’-ethynylferrocene carboxylic acid led to the formation of

[Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡CH)(CO)(PPh3)2] (8) in 69% yield (Scheme 2). The

31P{1H} NMR spectrum gave rise to a new resonance at 35.5 ppm – a similar value to that

found for [{Ru(C(C≡CPh)=CHPh)(CO)(PPh3)2}2(µ-dcbpy)] (2). 1H NMR analysis proved

diagnostic with the presence of the new ligand being confirmed by resonances at 3.38, 3.88,

4.01 and 4.12 ppm for the C5H4 rings and the acetylenic proton of the terminal alkyne

appearing as a singlet at 3.23 ppm. The retention of the enynyl ligand was indicated by the

broadened singlet at 5.61 (Hβ) in this spectrum and the presence of the C≡C absorption for

the C≡CPh unit at 2143 cm-1. Alongside this feature was observed a band for the terminal

alkyne at 2100 cm-1, the carbonyl at 1908 cm-1 and the carboxylate unit at 1501 cm-1. The

formulation of 8 was further confirmed by elemental analysis.

Scheme 2. Formation of heteromultimetallic complexes based on a bifunctional ferrocenyl unit;

DBU = 1,8-diazabicyclo[5.4.0]undec-7-ene.

The reaction of alkynes with gold halide precursors under basic conditions is well

known to result in alkynyl gold complexes.27 These compounds have been implicated in many

organic transformations catalysed by gold(I) compounds.28,29 They have also been used in

pioneering work by Lang and co-workers to create heteromultimetallic complexes.30 Reaction

of 8 with 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) and [AuCl(PPh3)] resulted in the formation

of the acetylide complex [Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡CAuPPh3)(CO)(PPh3)2]

(9), as shown in Scheme 2. The successful addition of the gold-phosphine unit was indicated

by a new singlet in the 31P{1H} NMR spectrum at 42.0 ppm, to lower field of the resonance at

35.3 ppm assigned to the ruthenium-bound triphenylphosphine ligands. The absence of the

acetylenic proton in the 1H NMR spectrum also provided indirect evidence for the formation of

this bimetallic complex. The 1,1’-bis(diphenylphosphino)ferrocene compound [dppf(AuCl)2]

provides a versatile starting point for multimetallic complexes, particularly through the

formation of gold thiolates.6g,31 Treatment of [dppf(AuCl)2] with two equivalents of 8 in the

presence of base (DBU) led to the formation of the heteroheptametallic Fe3Ru2Au2 complex,

[Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡C)(CO)(PPh3)2]2(Au2dppf) (10). The 31P{1H} NMR

spectrum revealed two resonances at 35.7 (RuPPh3) and 36.6 (Au-dppf) ppm, while the 1H

NMR spectrum displayed additional cyclopentadienyl resonances attributed to the dppf unit.

Good agreement between calculated and experimentally determined elemental analysis

values confirmed the overall formulation.

Having exploited the reactivity of the terminal alkynyl group in 8 to form acetylides, the

insertion of the alkyne into metal hydride bonds was next investigated – the same reaction

used to form the vinyl complexes was employed in this work. Compound 8 was found to react

rapidly with the hydride complex [RuHCl(CO)(BTD)(PPh3)2] to form

[Ru{C(C≡CPh)=CHPh}{O2CC5H4FeC5H4CH=CH(RuCl(CO)(BTD)(PPh3)2)}(CO)(PPh3)2] (11)

in a 100% atom efficient reaction (Scheme 2). The new resonance at 26.9 ppm in the 31P{1H}

NMR spectrum, shifted slightly upfield with respect to the resonance of the carboxylate metal

unit (35.4 ppm) was assigned to the new vinyl complex. 1H NMR analysis revealed resonances

for the protons of both the enynyl (5.60 ppm) and the new vinyl units (at 5.41 and 7.82 ppm).

Only one broad infrared absorption was observed for the complex, at 1918 cm-1, due to the

similarity of the carbonyl environments at each metal centre. However, the analogous osmium

complex,

[Ru{C(C≡CPh)=CHPh}{O2CC5H4FeC5H4CH=CH(OsCl(CO)(BTD)(PPh3)2)}(CO)(PPh3)2] (12),

gave rise to an absorption at 1921 cm-1 for the carbonyl on the ruthenium centre with a

shoulder at 1898 cm-1 for the CO ligand bonded to the more electron-rich osmium centre. The

differences in the electronic environments of the two metal centres were also reflected in the

31P{1H} spectrum, in which the phosphorus nuclei of the osmium centre resonated at much

lower chemical shift (-3.1 ppm) than those of the ruthenium centre (35.4 ppm). Complex 12 is

one of only a small number6g,32 of complexes to combine all the metals of group 8 in the

periodic table.

Complex 10 presents an unusual series of metal units which are typically stable

towards oxidation, with three ferrocenyl units in two different environments and two ruthenium

atoms in the same environment. It was therefore decided to explore briefly the electrochemical

behaviour of the heteroheptametallic complex. For comparison purposes, data were also

collected for precursors [dppf(AuCl)2] and the compound

[Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡CH)(CO)(PPh3)2] (8) (Figure 5). Complex 8 shows

two redox processes at 0.24 and 0.39 V respectively (vs Fc/Fc+). After correcting for

resistance, it was found that the former is electrochemically reversible (ΔE = 62 mV, ipa and ipc

proportional to square root of scan rate) whereas the latter is only quasi-reversible (ΔE = 102

mV, ipa proportional and ipc not proportional to scan rate, Figure S4-2). As the two redox

processes were somewhat broad and close together (ΔE1/2 = 141 mV) it was not possible to

determine ipa/ipc for either process. Comparison with literature data33,34 led us to assign the

lower potential process to the Fe(II/III) couple, while the wave at higher potential is related to

the ruthenium alkenyl moiety.35,6e

-0.2 0.0 0.2 0.4 0.6 0.8 1.0

E / V vs Fc / Fc+

2 A

Figure 5. Cyclic voltammogram for [dppf(AuCl)2] (blue), 8 (red) and 10 (black). Conditions:

0.1 M TBAPF6/DCM, 100 mV/s, glassy carbon electrode.

The cyclic voltammogram of 10 shows multiple redox processes, the origins of which

are difficult to assign with cyclic voltammetry alone. However, based on a comparison with the

CV of 8 and the starting material [dppf(AuCl)2], some tentative assignments can be made. It

is likely that the redox process at 0.64 V corresponds to the [dppf(AuCl)2] moiety; if the scan

exceeds this potential, the CV loses much of its reversibility, which is consistent with the

dissociation of the molecule upon oxidation of the central dppf moiety (Figure S4-5). The redox

process at 0.35 V is possibly related to the ruthenium alkenyl fragment. The redox process at

0.04 V does not appear in any of the component parts, but it is likely that this corresponds the

ethynylferrocenecarboxylate ligand which has become easier to oxidise upon conjugation to

gold. A smaller redox event can be observed between the major processes at 0.35 and 0.04

V. As the oxidative wave is broad and overlaps strongly with the waves either side, it is difficult

to assign a formal potential to this process and it is not clear as to its origins. A possible

explanation may be due to communication between the linked ethynylferrocenecarboxylate

ligands within the framework of 10 although this too is difficult to prove by CV alone. A scan

rate analysis was performed but scanning too slowly (20 and 50 mV/s) resulted in deposition

on the electrodes, while inclusion of the signal at 0.64 V resulted in chemical irreversibility as

evidenced in figure S4-5. Within the limits of the chemistry exhibited, we were able to

demonstrate that the signals at 0.04 and 0.35 V were both quasi-reversible (Figure S4-4).

Further investigations lie beyond the scope of this present contribution.

Conclusions

This contribution illustrates how polyfunctional linkers combining carboxylic acid and alkynyl

or pyridyl donors can be used to generate a series of homo- and heteronuclear, bi- and

trimetallic of Re(I), Ru(II), Os(II) and Au(I) in a controlled, selective and stepwise manner. The

literature compound [ReCl(CO)3(µ-H2dcbpy)] (4) leads to trimetallic complexes, which are not

accessible from the parent H2dcbpy ligand, which only results in bimetallic compounds. A

comparison of the photophysical properties of 4 and [{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2

(7) illustrates the effect of adding Ru(II) termini, which leads to enhanced luminescent

behaviour. The second linker studied, 1,1’-ethynylferrocene carboxylic acid, brings together

oxygen donor and alkynyl functionalities, allowing initial coordination of a ruthenium(II) vinyl

unit to give [Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡CH)(CO)(PPh3)2] (8). The pendant

ethynyl unit can be exploited to form either acetylide or vinyl bridges to a further metal unit,

allowing the extension to heterotrimetallic FeRuOs and FeRuAu compounds. The

electrochemical behaviour of the heteroheptametallic Fe3Ru2Au2 complex (10) was explored,

and through a comparison to that of 8 and [dppf(AuCl)2], a reasonable assignment of the

individual metal units could be made. This study illustrates how linkers with carefully selected

donor groups can be employed to generate a wide variety of multimetallic complexes with a

variety of different metals from across the d-block. Once combined in a heterometallic

assembly, the photophysical and electrochemical properties can be interrogated as a function

of the metal units employed.

Acknowledgements

K.A.J. would like to thank the Ministry of Higher Education, Malaysia for a scholarship

on the IPTA Academic Training Scheme and for an Academic Staff Scholarship from

the Universiti Teknologi MARA, Malaysia. L.M. gratefully acknowledges the support of

the Royal Society for a RS-CNR International Fellowship.

References

1. a) M. Shibasaki, M. Kanai, S. Matsunaga and N. Kumagai, Acc. Chem. Res., 2009, 42,

1117-1127; b) M. Weber, J. E. M. N. Klein, B. Miehlich, W. Frey and R. Peters,

Organometallics, 2013, 32, 5810-5817; c) H. Sasai, T. Suzuki, S. Arai, T. Arai and M.

Shibasaki, J. Am. Chem. Soc., 1992, 114, 4418-4420; d) J. H. H. Ho, J. Wagler, A. C.

Willis and B. A. Messerle, Dalton Trans., 2011, 40, 11031-11042; e) W.-Z. Lee, T.-L.

Wang, H.-C. Chang, Y.-T. Chen and T. S. Kuo, Organometallics, 2012, 31, 4106-4109;

f) Y. Yamaguchi, K. Yamanishi, M. Kondo and N. Tsukada, Organometallics, 2013, 32,

4837-4842; g) B. Wu, J. C. Gallucci, J. R. Parquette and T. V. RajanBabu, Chem. Sci.,

2014, 5, 1102-1117.

2. a) X. He, F. Herranz, E. C.-C. Cheng, R. Vilar and V. W.-W. Yam, Chem. Eur. J., 2010,

16, 9123–9131; b) J. S. Mendy, M. A. Saeed, F. R. Fronczek, D. R. Powell and Md. A.

Hossain, Inorg. Chem., 2010, 49, 7223–7225; c) M. E. Moragues, J. Esteban, J. V.

Ros-Lis, R. Martínez-Máñez, M.D. Marcos, M. Martínez, J. Soto and F. Sancenón, J.

Am. Chem. Soc., 2011, 133, 15762-15772; d) J. Esteban, J. V. Ros-Lis, R. Martínez-

Máñez, M. D. Marcos, M. Moragues, J. Soto and F. Sancenón, Angew. Chem. Int. Ed.,

2010, 49, 4934-4937; Angew. Chem., 2010, 122, 5054-5057.

3. a) J. B. Livramento, E. Tóth, A. Sour, A. Borel, A. E. Merbach and R. Ruloff, Angew.

Chem. Int. Ed., 2005, 44, 1480-1484; b) J. B. Livramento, A. Sour, A. Borel, A. E.

Merbach and E. Tóth, Chem. Eur. J., 2006, 12, 989-1003; c) L. Moriggi, A. Aebischer,

C. Cannizzo, A. Sour, A. Borel, J.-C. G. Bunzli and L. Helm, Dalton Trans., 2009, 2088-

2095; d) D. Kasala, T. S. Lin, C.-Y. Chen, G.-C. Liu, C.-L. Kao, T.-L. Cheng and Y.-M.

Wang, Dalton Trans., 2011, 40, 5018-5025; e) P. Mieville, H. Jaccard, F. Reviriego, R.

Tripier and L. Helm, Dalton Trans., 2011, 40, 4260-4267; f) G. Dehaen, P. Verwilst, S.

V. Eliseeva, S. Laurent, L. Vander Elst, R. N. Muller, W. M. De Borggraeve, K.

Binnemans and T. N. Parac-Vogt, Inorg. Chem., 2011, 50, 10005–10014; g) G.

Dehaen, S. V. Eliseeva, K. Kimpe, S. Laurent, L. Vander Elst, R. N. Muller, W. Dehaen,

K. Binnemans and T. N. Parac-Vogt, Chem. Eur. J., 2012, 18, 293–302; h) P. Verwilst,

S. V. Eliseeva, L. Vander Elst, C. Burtea, S. Laurent, S. Petoud, R. N. Muller, T. N.

Parac-Vogt and W. M. De Borggraeve, Inorg. Chem., 2012, 51, 6405−6411; i) G.

Dehaen, S. V. Eliseeva, P. Verwilst, S. Laurent, L. Vander Elst, R. N. Muller, W. De

Borggraeve, K. Binnemans and T. N. Parac-Vogt, Inorg. Chem., 2012, 51, 8775−8783.

4. a) H. Eddaoudi, M. Li, M. O’Keeffe, O. M. Yaghi, Nature, 1999, 402, 276–279; b) J. R.

Long, O. M. Yaghi, Chem. Soc. Rev., 2009, 38, 1213–1214 and subsequent reviews

in the same issue; c) Janiak, C.; Vieth, J. K. New J. Chem., 2010, 34, 2366–2388;

5. a) C. Janiak, Dalton Trans., 2003, 2781–2804; b) H. Arora, R. Mukherjee, New J.

Chem., 2010, 34, 2357–2365.

6. a) A. Toscani, E. K. Heliövaara, J. B. Hena, A. J. P. White, J. D. E. T. Wilton-Ely,

Organometallics, 2015, 34, 494−505; b) Y. H. Lin, L. Duclaux, F. Gonzàlez de Rivera,

A. L. Thompson, J. D. E. T. Wilton-Ely, Eur. J. Inorg. Chem., 2014, 2065-2072; c) V.

L. Hurtubise, J. M. McArdle, S. Naeem, A. Toscani, A. J. P. White, N. J. Long, J. D. E.

T. Wilton-Ely, Inorg. Chem., 2014, 53, 11740−11748; d) S. Naeem, A. Ribes, A. J. P.

White, M. N. Haque, K. B. Holt, J. D. E. T. Wilton-Ely, Inorg. Chem., 2013, 52, 4700-

4713; e) Y. H. Lin, N. H. Leung, K. B. Holt, A. L. Thompson, J. D. E. T. Wilton-Ely,

Dalton Trans., 2009, 7891-7901; f) R. Sherwood, F. Gonzàlez de Rivera, J. H. Wan,

Q. Zhang, A. J. P. White, O. Rossell, G. Hogarth, J. D. E. T. Wilton-Ely, Inorg. Chem.,

2015, 54, 4222−4230; g) J. A. Robson, F. Gonzalez de Rivera, K. A. Jantan, M. N.

Wenzel, A. J. P. White, O. Rossell, J. D. E. T. Wilton-Ely, Inorg. Chem., 2016, 55,

12982−12996; h) A. Toscani, K. A. Jantan, J. B. Hena, J. A. Robson, E. J. Parmenter,

V. Fiorini, A. J. P. White, S. Stagni, J. D. E. T. Wilton-Ely, Dalton Trans., 2017, 46,

5558-5570.

7. a) R. Packheiser, P. Ecorchard, T. Rüffer, B. Walfort, H. Lang, Eur. J. Inorg. Chem.,

2008, 4152–4165; b) R. Packheiser, A. Jakob, P. Ecorchard, B. Walfort, H. Lang,

Organometallics, 2008, 27, 1214–1226; c) R. Packheiser, P. Ecorchard, B. Walfort, H.

Lang, J. Organomet. Chem., 2008, 693, 933–946; d) R. Packheiser, P. Ecorchard, T.

Rüffer, M. Lohan, B. Bräuer, F. Justaud, C. Lapinte, H. Lang, Organometallics, 2008,

27, 3444–3457; e) R. Packheiser, P. Ecorchard, T. Rüffer, H. Lang, Organometallics,

2008, 27, 3534–3546; f) H. Lang, P. Zoufalá, S. Klaib, A. del Villar, G. Rheinwald, J.

Organomet. Chem., 2007, 692, 4168–4176; g) R. Packheiser, H. Lang, Eur. J. Inorg.

Chem., 2007, 3786–3788; h) R. Packheiser, B. Walfort, H. Lang, Organometallics,

2006, 25, 4579–4587; h) J. Maurer, B. Sarkar, W. Kaim, R. F. Winter, S. Zališ, Chem.

Eur. J., 2007, 13, 10257-10272.

8. R. Packheiser, P. Ecorchard, T. Rüffer, H. Lang, Chem. Eur. J., 2008, 14, 4948–4960;

9. a) J. D. E. T. Wilton-Ely, D. Solanki, G. Hogarth, Eur. J. Inorg. Chem., 2005, 4027-

4030; b) E. R. Knight, D. Solanki, G. Hogarth, K. B. Holt, A. L. Thompson, J. D. E. T.

Wilton-Ely, Inorg. Chem., 2008, 47, 9642-9653; c) M. J. Macgregor, G. Hogarth, A. L.

Thompson, J. D. E. T. Wilton-Ely, Organometallics, 2009, 28, 197-208; d) E. R. Knight,

A. R. Cowley, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton Trans., 2009, 607-609; e) E.

R. Knight, N. H. Leung, Y. H. Lin, A. R. Cowley, D. J. Watkin, A. L. Thompson, G.

Hogarth, J. D. E. T. Wilton-Ely, Dalton Trans., 2009, 3688-3697; f) E. R. Knight, N. H.

Leung, A. L. Thompson, G. Hogarth, J. D. E. T. Wilton-Ely, Inorg. Chem., 2009, 48,

3866-3874; g) K. Oliver, A. J. P. White, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton

Trans., 2011, 40, 5852-5864; h) G. Hogarth, E.-J. C.-R. C. R. Rainford-Brent, S. E.

Kabir, I. Richards, J. D. E. T. Wilton-Ely, Q. Zhang, Inorg. Chim. Acta, 2009, 362, 2020–

2026; i) S. Naeem, E. Ogilvie, A. J. P. White, G. Hogarth, J. D. E. T. Wilton-Ely, Dalton

Trans., 2010, 39, 4080-4089; j) R. B. Bedford, A. F. Hill, C. Jones, A. J. P. White, D. J.

Williams, J. D. E. T. Wilton-Ely, J. Chem. Soc., Dalton Trans., 1997, 139-140; k) S.

Sung, H. Holmes, L. Wainwright, A. Toscani, G. J. Stasiuk, A. J. P. White, J. D. Bell,

J. D. E. T. Wilton-Ely, Inorg. Chem., 2014, 53, 1989-2005

10. a) P. Patel, S. Naeem, A. J. P. White, J. D. E. T. Wilton-Ely, RSC Adv., 2011, 2, 999-

1008; b) S. Naeem, A. L. Thompson, A. J. P. White, L. Delaude, J. D. E. T. Wilton-Ely,

Dalton Trans., 2011, 40, 3737-3747; c) S. Naeem, A. L. Thompson, L. Delaude, J. D.

E. T. Wilton-Ely, Chem. Eur. J., 2010, 16, 10971-10974; d) J. D. E. T. Wilton-Ely, D.

Solanki, G. Hogarth, Inorg. Chem., 2006, 45, 5210-5214; e) S. Naeem, A. J. P. White,

G. Hogarth, J. D. E. T. Wilton-Ely, Organometallics, 2010, 29, 2547-2556; f) R. B.

Bedford, A. F. Hill, C. Jones, A. J. P. White, D. J. Williams, J. D. E. T. Wilton-Ely,

Organometallics, 1998, 17, 4744-4753; g) B. Buriez, D. J. Cook, K. J. Harlow, A. F.

Hill, T. Welton, A. J. P. White, D. J. Williams, J. D. E. T. Wilton-Ely, J. Organomet.

Chem., 1999, 578, 264-267.

11. a) B. O’Regan, M. Grätzel, Nature, 1991, 353, 737-740; b) M. K. Nazeeruddin, A. Key,

L. Rodicio, R. Humphrey-Baker, E. Müller, P. Liska, N. Vlachopoulos, M. Grätzel, J.

Am. Chem. Soc., 1993, 115, 6382-6390; c) J.-F. Yin, M. Velayudham, D. Bhattacharya,

H.-C. Lin, K.-L. Lu, Coord. Chem. Rev., 2012, 256, 3008-3035.

12. M. R. Torres, A. Vegas, A. Santos and J. Ros, J. Organomet. Chem., 1986, 309,

169−177.

13. H. Werner, M. A. Esteruelas and H. Otto, Organometallics, 1986, 5, 2295−2299.

14. M. C. J. Harris, A. F. Hill, Organometallics, 1991, 10, 3903-3906.

15. For an overview of vinyl chemistry of ruthenium(II), see: a) M. K. Whittlesey, in

Comprehensive Organometallic Chemistry III; R. H. Crabtree, D. M. P. Mingos and M.

I. Bruce, Eds.; Elsevier: Oxford, U.K., 2006; Vol. 6; b) A. F. Hill, in Comprehensive

Organometallic Chemistry II; E. W. Abel, F. G. A. Stone and G. Wilkinson.; Eds.;

Pergamon Press: Oxford, U.K., 1995, Vol. 7.

16. a) M. E. Moragues, A. Toscani, F. Sancenón, R. Martínez-Mañez, A. J. P. White and

J. D. E. T. Wilton-Ely, J. Am. Chem. Soc., 2014, 136, 11930−11933; b) A. Toscani, C.

Marín-Hernández, M. E. Moragues, F. Sancenón, P. Dingwall, N. J. Brown, R.

Martínez-Mañez, A. J. P. White and J. D. E. T. Wilton-Ely, Chem. Eur. J., 2015, 21,

14529 – 14538; c) C. de la Torre, A. Toscani, C. Marín-Hernández, J. A. Robson, M.

C. Terencio, A. J. P. White, M. J. Alcaraz, J. D. E. T. Wilton-Ely, R. Martínez-Máñez,

F. Sancenón, J. Am. Chem. Soc., 2017, 139, 18484-18487; d) A. Toscani, C. Marín-

Hernández, F. Sancenón, J. D. E. T. Wilton-Ely and R. Martínez-Máñez, Chem.

Commun., 2016, 52, 5902-5911.

17. A. Santos, J. López, L. Matas, J. Ros, A. Galán, A. M. Echavarren, Organometallics,

1993, 12, 4215-4218.

18. A. Santos, J. López, A. Galán, J. J. González, P. Tinoco, A. M. Echavarren,

Organometallics, 1997, 16, 3482-3488.

19. E. B. Boyar, P. A. Harding, S. D. Robinson, C. P. Brock, J. Chem. Soc., Dalton Trans.,

1986, 1771-1778.

20. W. Hieber and H. Schulten, Z. Anorg. Allg. Chem., 1939, 243, 164-173.

21. J. M. Smieja and C. P. Kubiak, Inorg. Chem., 2010, 49, 9283–9289.

22. A. Sinopoli, F. A. Black, C. J. Wood, E. A. Gibson and P. I. P. Elliott, Dalton Trans.

2017, 46, 1520-1530

23. R. A. Kirgan, B. P. Sullivan and D. P. Rillema, Top. Curr. Chem., 2007, 281, 45–100

24. L. Flamigni, A. Barbieri, C. Sabatini, B. Ventura and F. Barigelletti, Top. Curr. Chem.,

2007, 281, 143–203.

25. A. R. Cowley, A. L. Hector, A. F. Hill, A. J. P. White, D. J. Williams and J. D. E. T.

Wilton-Ely, Organometallics, 2007, 26, 6114−6125.

26. D. Huber, H. Hubner, P. Gmeiner, J. Med. Chem., 2009, 52, 6860-6870.

27. J. C. Lima, L. Rodríguez, Chem. Soc. Rev., 2011, 40, 5442-5456.

28. Z. Li, C. Brouwer, C. He, Chem. Rev., 2008, 108, 3239–3265.

29. I. Braun, A. M. Asiri, A. S. K. Hashmi, ACS Catal., 2013, 3, 1902−1907.

30. a) R. Packheiser, A. Jakob, P. Ecorchard, B. Walfort, H. Lang, Organometallics, 2008,

27, 1214–1226; b) H. Lang, Polyhedron, 2018, 139, 50–62.

31. J. D. E. T. Wilton-Ely, A. Schier, N. W. Mitzel, H. Schmidbaur, J. Chem. Soc., Dalton

Trans., 2001, 1058–1062.

32. N. J. Long, A. J. Martin, A. J. P. White, D. J. Williams, M. Fontani, F. Laschi, P. Zanello,

Dalton Trans., 2000, 3387–3392.

33. V. Lozan, A. Buchholz, W. Plass, B. Kersting, Chem. Eur. J., 2007, 13, 7305-7316.

34. J. K. Pudelski, M. R. Callstrom, Organometallics, 1994, 13, 3095-3109.

35. P. Mücke, M. Linseis, S. Zališ, R. F. Winter, Inorg. Chim. Acta, 2011, 374, 36-50.

Supporting Information

Heteromultimetallic compounds based on polyfunctional carboxylate linkers

Khairil A. Jantan, James A. McArdle, Lorenzo Mognon, Valentina Fiorini, Luke A. Wilkinson,

Andrew J. P. White, Stefano Stagni, Nicholas J. Long* and James D. E. T. Wilton-Ely*

S1. Experimental page 1

S2. Crystallography page 26

S3. Photophysics page 27

S4. Electrochemistry page 30

S5. References page 32

S1. Experimental

General Comments. Unless otherwise stated, all experiments were carried out in the air, and

the complexes obtained appear stable towards the atmosphere, whether in solution or the

solid-state. Reagents and solvents were used as received from commercial sources.

Petroleum ether is the fraction boiling in the 40–60 °C range. The following complexes were

prepared following literature routes: cis-[RuCl2(dppm)2],S1

[Ru(CH=CHC6H4Me4)Cl(CO)(BTD)(PPh3)2],S2 [Ru(C(C≡CPh)=CHPh)Cl(CO)(PPh3)2],S3

[ReCl(CO)3(dcbpy)],S4 (HC≡CC5H4)Fe(C5H4CO2H),S5 [OsHCl(CO)(BTD)(PPh3)2] (M = Ru,S6

OsS7), [AuCl(PPh3)]S8 and [(dppf)AuCl2].S9 Electrospray (ES) and Fast Atom Bombardment

(FAB) mass data were obtained using Micromass LCT Premier and Autospec Q instruments,

respectively. Infrared data were obtained using a Perkin-Elmer Spectrum 100 FT-IR

spectrometer employing an ATR method, and characteristic triphenylphosphine-associated

infrared data are not reported. NMR spectroscopy was performed at 25 °C using Bruker AV400

or AV 500 spectrometers in CDCl3 unless stated otherwise. All coupling constants are in Hertz.

Resonances in the 31P{1H} NMR spectrum due to the hexafluorophosphate counteranion were

observed where the formulation indicates but are not included below. Elemental analysis data

were obtained from London Metropolitan University. Solvates were confirmed by integration

of the 1H NMR spectra. The procedures given provide materials of sufficient purity for synthetic

and spectroscopic purposes.

[{Ru(CH=CHC6H4Me-4)(CO)(PPh3)2}2(µ-dcbpy)] (1)

A solution of 2,2’-bipyridine-4,4’-dicarboxylic acid (10.0 mg, 0.041 mmol) and sodium

methoxide (6.7 mg, 0.123 mmol) in methanol (10 mL) was stirred at room temperature for 30

minutes. A dichloromethane (20 mL) solution of [Ru(CH=CHC6H4Me–4)Cl(CO)(BTD)(PPh3)2]

(77 mg, 0.082 mmol) was added and stirred for another 2 h at room temperature. All the

solvent was removed under vacuum and the crude product was dissolved in dichloromethane

(10 mL) and filtered through Celite to remove NaCl, NaOMe and excess ligand. The solvent

was again removed using rotary evaporator. Diethyl ether (10 mL) was added, and the

resulting mixture triturated in the ultrasonic bath. The dark brown precipitate obtained was

filtered under vacuum, washed with diethyl ether (10 mL) and dried. Yield: 34 mg (47%). The

product can be recrystallised from dichloromethane-diethyl ether mixtures. IR: 1928 (CO),

1573, 1544 (OCO), 1481, 1433, 1185, 1090, 979, 875, 836, 741, 692 cm–1. 1H NMR (CDCl3):

2.23 (s, 6H, CH3), 5.89 (d, 2H, Hβ, JHH = 15.2 Hz), 6.35, 6.82 (AB, 8H, C6H4, JAB = 7.8 Hz),

6.92 (dd, 2H, bpy, JHH = 4.9, 1.4 Hz), 7.30 – 7.43, 7.50 (m x 2, 60H, C6H5), 7.66 (m, 2H, bpy),

7.82 (dt, 2H, Hα, JHH = 15.2 Hz, JHP = 2.7), 8.46 (d, 2H, bpy, JHH = 4.9) ppm. 31P{1H} NMR

(CDCl3): 38.2 (s, PPh3) ppm. MS (ES +ve) m/z (abundance): 1894 (4) [M+4Na+H2O]+, 1543

(3) [M–PPh3+Na]+, 1113 (50) [M–vinyl–CO–2PPh3]+, 991 (100) [M–CO–3PPh3+Na]+. Elem.

Anal. Calcd. for C104H84N2O6P4Ru2·2.5CH2Cl2 (MW = 1996.16): C 64.1, H 4.5, N 1.4%. Found:

C 63.7, H 4.2, N 1.8%

Figure S1-1. 31P{1H} NMR spectrum of compound 1 in CDCl3.

Figure S1-2. 1H NMR spectrum of compound 1 in CDCl3.

Figure S1-3. Solid-state infrared spectrum of compound 1.

[{Ru(C(C≡CPh)=CHPh)(CO)(PPh3)2}2(µ-dcbpy)] (2)

A methanolic solution (10 ml) of 2,2’-bipyridine-4,4’-dicarboxylic acid (20 mg, 0.082 mmol) and

sodium methoxide (13.3 mg, 0.246 mmol) was stirred for 30 minutes at room temperature and

treated with a dichloromethane solution (10 mL) of [Ru(C(C≡CPh)=CHPh)Cl(CO)(PPh3)2]

(146.3 mg, 0.164 mmol). The reaction was stirred for 2h at room temperature. The solvent

was removed under vacuum (rotary evaporator) and the resulting red product was dissolved

in the minimum amount of dichloromethane. This was filtered through Celite and the solvent

removed by rotary evaporation. Diethyl ether (10 mL) was added, and subsequent ultrasonic

titruration provided a dark red precipitate, which was filtered, washed with diethyl ether (10

mL) and dried. Yield: 80 mg (50%). The product is slightly soluble in diethyl ether. IR: 2163

(C≡C), 1929 (CO), 1522 (OCO), 1482, 1432, 1186, 1094, 877, 743, 691 cm–1. 1H NMR (CDCl3):

6.01 (s(br), 2H, Hβ), 6.92 (dd, 2H, bpy, JHH = 6.2), 7.00 (m, 6H, C6H5), 7.09 (t, 6H, CC6H5,

JHH = 7.5 Hz), 7.20 - 7.22 (m, 34H, PC6H5), 7.35 (m, 4H, CC6H5), 7.42 (t, 4H, CC6H5, JHH = 7.5

Hz), 7.54 - 7.59 (m, 26H, PC6H5), 7.78 (m, 2H, bpy), 8.46 (dd, 2H, bpy) ppm. 31P{1H} NMR

(CDCl3): 38.2 (s, PPh3) ppm. MS (ES +ve) m/z (abundance): 1980 (10) [M+H+Na]+, 897

(100) [M–4PPh3–CO+H2O]+. Elem. Anal. Calcd. for C118H88N2O6P4Ru2 (MW = 1956.01): C

72.4, H 4.5, N 1.4%. Found: C 72.3, H 4.3, N 1.6%.



Figure S1-6. Solid-state infrared spectrum of compound 2.

[{Ru(dppm)2}2(µ-dcbpy)](PF6)2 (3·2PF6)

A solution of 2,2’-bipyridine-4,4’-dicarboxylic acid (10.0 mg, 0.041 mmol) and sodium

methoxide (8.9 mg, 0.164 mmol) in methanol (10 mL) was stirred for 30 minutes at room

temperature. A solution of cis-[RuCl2(dppm)2] (77 mg, 0.082 mmol) in dichloromethane (20

mL) was then added along with ammonium hexafluorophosphate (22.6 mg, 0.123 mmol). The

reaction mixture was stirred for 2 h at room temperature. All the solvent was then removed

using a rotary evaporator and the crude product was re-dissolved in dichloromethane (10 mL)

and filtered through Celite. Ethanol (20 mL) was added and the solvent volume slowly reduced

on a rotary evaporator until the formation of a brown solid. The precipitate was filtered, washed

with petroleum ether (10 mL) and dried under vacuum. The product is partially soluble in

ethanol, contributing to a reduced yield. Yield: 48 mg (51%). IR: 1593, 1521 (OCO), 1482,

1426, 1186, 1093, 835 (PF) cm–1. 1H NMR (CDCl3): 4.16, 4.76 (m x 2, 2 x 4H, PCH2P), 6.26

(m, 8H, C6H5), 6.99 − 7.54 (m, 56H + 2H, C6H5 + bpy), 7.65, 7.80 (m x 2, 2 x 8H, C6H5), 8.55

(s, 2H, bpy), 8.91 (d, 2H, bpy, JHH = 4.3 Hz) ppm. 31P{1H} NMR (CDCl3): −11.9, 8.7

(pseudotriplet x 2, dppm, JPP = 38.8 Hz) ppm. MS (MALDI +ve) m/z (abundance): 2128 (12)

[M+H+PF6]+, 1981 (11) [M+H]+. Elem. Anal. Calcd. for C112H94F12N2O4P10Ru2·CH2Cl2 (MW =

2356.75): C 57.6, H 4.1, N 1.2%. Found: C 57.3, H 4.2, N 1.0%. [{Ru(dppm)2}2(µ-

dcbpy)](PF6)2 (3·2BPh4) was prepared in an identical manner, using sodium

tetraphenylborate. Spectroscopic data for the cation were found to be identical to those for

3·2PF6.

Figure S1-7. 31P{1H} NMR spectrum of compound 3·2PF6 in CDCl3.

Figure S1-8. 1H NMR spectrum of compound 3·2PF6 in CDCl3.

Figure S1-9. Solid-date IR spectrum of compound 3·2PF6.

[ReCl(CO)3(µ-H2dcbpy)] (4)

Re(CO)5Cl (193 mg, 0.53 mmol) was dissolved in an hot toluene (50 mL) and methanol (20

mL). 4,4’-dicarboxyl-2,2’-bipyridine (130 mg, 0.53 mmol) was added to the solution, and the

reaction mixture was stirred under reflux for 1h. During this time, the colour of the solution

changed from colourless to orange. The solution was kept at –20 degrees for 1h to precipitate

the unreacted starting material which was then filtered. The resulting orange solution was

evaporated to dryness to yield the product. Yield: 233 mg (80 %). IR: 2030 (CO), 1902 (CO),

1875 (CO), 1734, 1511 (OCO), 1426, 1214, 1095, 832, 772, 731, 691, 663 cm–1. 1H NMR (d6-

DMSO): 8.14 (dd, 2H, bpy, JHH = 5.7, 1.7 Hz), 9.15 (dd, 2H, bpy, JHH = 1.7, 0.8 Hz), 9.22

(dd, 2H, bpy, JHH = 5.7, 0.8 Hz), 14.39 (s(br), 2H, CO2H) ppm. The data obtained were found

to be in good agreement with those reported in the literature.S4

Figure S1-10. 1H NMR spectrum of compound 4 in DMSO (solvent peaks removed).

Figure S1-11. Solid-state IR spectrum of compound 4.

[{Ru(CH=CHC6H4Me-4)(CO)(PPh3)2}2(µ-dcbpy)ReCl(CO)3] (5)

A solution of 4 (30 mg, 0.055 mmol) and sodium methoxide (11.9 mg, 0.22 mmol) in methanol

(10 mL) was stirred for 30 minutes at room temperature. A solution of [Ru(CH=CHC6H4Me–

4)Cl(CO)(BTD)(PPh3)2] (102.7 mg, 0.109 mmol) in dichloromethane (10 mL) was added and

stirred for another 2h. Ethanol (10 mL) was added and the solvent volume slowly reduced on

a rotary evaporator until the formation of a brown solid was complete. The precipitate was

filtered, washed with ethanol (10 mL) and dried under vacuum. Yield: 79 mg (69 %). IR: 2019

(CO), 1918 (CO), 1890 (CO), 1531 (OCO), 1481, 1433, 1391, 1184, 1090, 979, 827, 743, 692

cm–1. 1H NMR (CDCl3): 2.23 (s, 6H, CH3), 5.94 (d, 2H, Hβ, JHH = 15.0 Hz), 6.38, 6.82 (AB,

8H, C6H4, JAB = 7.7 Hz), 7.01 (dd, 2H, bpy, JHH = 5.6, 1.4 Hz), 7.26 (m, 2H, bpy), 7.36, 7.52 (m

x 2, 60H, C6H5), 7.84 (dt, 2H, Hα, JHH = 15.0 Hz, JHP = 2.8 Hz), 8.68 (d, 2H, bpy, JHH = 5.6 Hz)

ppm. 13C{1H} NMR (CD2Cl2): 206.4 (t, RuCO, JPC = 15.0 Hz), 197.8 (s, 2 x ReCO), 197.6 (s,

ReCO), 172.8 (s, CO2), 155.1, 152.6 (s x 2, 2 x bpy), 151.0 (t, C, JPC = 11.5 Hz), 142.4 (s,

bpy), 138.0 (s, ipso/p-C6H4), 134.7 (tv, o/m-C6H5, JPC = 5.4 Hz), 133.7 (s, C), 132.2 (s, ipso/p-

C6H4), 131.1 (tv, ipso-C6H5, JPC = 22.0 Hz), 130.7 (s, p-C6H5), 128.7 (tv, o/m-C6H5, JPC = 5.5

Hz), 128.4 (s, o/m-C6H4), 125 (s, bpy), 124.6 (s, o/m-C6H4), 121.5 (s, bpy), 21.0 (s, p-C6H4)

ppm. 31P{1H} NMR (CDCl3): 38.1 (s, PPh3) ppm. MS (ES +ve) m/z (abundance): 1244 (12)

[M–3PPh3–3CO+H+Na]+, 1303 (4) [M–3PPh3]+. Elem. Anal. Calcd. for C107H84N2O9P4ReRu2

(MW = 2089.51): C 61.5, H 4.1, N 1.3%. Found: C 61.4, H 3.9, N 1.4%.


Figure S1-13. 13C{1H} NMR spectrum of compound 5 in CDCl3.

[{Ru(C(C≡CPh)=CHPh)(CO)(PPh3)2}2(µ-dcbpy)ReCl(CO)3] (6)

A solution of 4 (30 mg, 0.055 mmol) and sodium methoxide (11.9 mg, 0.22 mmol) in methanol

(10 ml) was stirred for 30 minutes at room temperature. A brown solution of

[Ru(C(C≡CPh)=CHPh)Cl(CO)(PPh3)2] (97.3 mg, 0.109 mmol) in dichloromethane (10 mL)

was added and stirred for another 2h. Ethanol (10 mL) was added and the solvent volume

slowly reduced on a rotary evaporator until the formation of a brown solid was complete. The

precipitate was filtered, washed with ethanol (10 mL) and dried under vacuum. Yield: 82 mg

(66 %). IR: 2019 (CO), 1917 (CO), 1890 (CO), 1531 (OCO), 1481, 1433, 1185, 1094, 826, 743,

691 cm–1. 1H NMR (CDCl3): 6.12 (s(br), 2H, Hβ), 6.89 (d, 2H, bpy, JHH = 5.6 Hz), 7.04 (m,

6H, CC6H5), 7.12 (t, 6H, CC6H5, JHH = 7.4 Hz), 7.21 - 7.35 (m, 36H, PC6H5), 7.39 -7.46 (m, 8H,

CC6H5), 7.59 (m, 24H + 2H, PC6H5 + bpy), 8.66 (d, 2H, bpy, JHH = 5.6 Hz) ppm. 31P{1H} NMR

(CDCl3): 37.9 (s, PPh3) ppm. MS (ES +ve) m/z (abundance): 1245 (4) [M–3PPh3–CO–

enynyl]+, 898 (100) [(M–PPh3–enynyl)/2]+. Elem. Anal. Calcd. for C121H88ClN2O9P4ReRu2 (MW

= 2261.70): C 64.3, H 3.9, N 1.2%. Found: C 64.1, H 3.8, N 1.2%.


[{Ru(dppm)2}2(µ-dcbpy)ReCl(CO)3](PF6)2 (7)

An orange solution of 4 (30 mg, 0.055 mmol) and sodium methoxide (11.9 mg, 0.22 mmol) in

methanol (10 mL) was stirred for 30 minutes at room temperature. A yellow solution of cis-

[RuCl2(dppm)2] (102.5 mg, 0.11 mmol) in dichloromethane (10 mL) was added to the mixture

leading to an immediate colour change to orange. Potassium hexafluorophosphate (40.5 mg,

0.22 mmol) was added and the reaction mixture was stirred for another 1 h at room

temperature. All the solvent was removed under vacuum and the crude product was dissolved

in dichloromethane (10 mL) and filtered through Celite to remove NaCl, NaOMe and excess

ligand. Ethanol (10 mL) was added and the solvent volume was slowly reduced on a rotary

evaporator until the formation of an orange solid. The precipitate was filtered, washed with

ethanol (10 mL) and dried under vacuum. Yield: 85 mg (60%). IR: 2020 (CO), 1919 (CO), 1892

(CO), 1515 (C-O), 1482, 1434, 1092, 839, 741, 692 cm–1. 1H NMR (CD2Cl2): 4.25, 4.80 (m x

2, 2 x 4H, PCH2P), 6.28 (m, 8H, C6H5), 7.03 − 7.93 (m, 72H + 2H, C6H5 + bpy), 7.92 (d, 2H,

bpy, JHH = 8.9 Hz), 9.18 (dd, 2H, bpy, JHH = 11.2, 5.2 Hz) ppm. 31P{1H} NMR (CD2Cl2): −11.5,

9.3 (pseudotriplet x 2, dppm, JPP = 38.9 Hz) ppm. MS (ES +ve) m/z (abundance): 1144 (100)

[M/2]+. Elem. Anal. Calcd. for C115H94ClF12N2O7P10ReRu2·2CH2Cl2 (MW = 2747.37): C 51.1, H

3.6, N 1.0%. Found: C 50.9, H 3.3, N 1.3%.

Figure S1-19. 31P{1H} NMR spectrum of compound 7 in CD2Cl2.

Figure S1-20. 1H NMR spectrum of compound 7 in CD2Cl2.


[Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡CH)(CO)(PPh3)2] (8)

1,1’-Ethynylferrocene carboxylic acid (132 mg, 0.520 mmol) was suspended in

dichloromethane (100 mL) and triethylamine (0.3 mL, 2.15 mmol) added. The reaction was

stirred until complete dissolution had occurred (30-45 minutes).

[RuCl{C(C≡CPh)CHPh}(CO)(BTD)(PPh3)2] (489 mg, 0.420 mmol) was added and the mixture

stirred for a further three hours. All solvent was removed under reduced pressure and the

resultant crude product dissolved in a minimum volume of dichloromethane and filtered

through Celite. Ethanol (100 mL) was added and the solvent volume was reduced (rotary

evaporation) to form a bright orange product. This was washed with cold ethanol (20 mL) and

n-hexane (20 mL) and dried under vacuum. Yield: 330 mg (69%). IR: 3298, 2143 (C≡C), 2100

(C≡C), 1908 (CO), 1501 (OCO), 1433, 1187, 1093 cm-1. 1H NMR (d6-acetone): 3.23 (s, 1H,

C≡CH); 3.38, 3.88, 4.01, 4.12 (s(br) x 4, 4 x 2H, C5H4), 5.61 (s(br), 1H, H), 6.94 - 7.80 (m,

30H + 10H, PC6H5 + CC6H5) ppm. 13C{1H} NMR (CD2Cl2): 207 (t, CO, JPC = 16.5 Hz), 181.3

(s, CO2), 144.2 (t, C, JPC unresolved), 140.2 (s, C), 135.1 (tv, o/m-PC6H5, JPC = 5.6 Hz),

131.9 (s, C6H5), 131.5 (tv, ipso-C6H5, JPC = 21.5 Hz), 130.4 (s, C6H5), 130.2 (s, p-C6H5), 130.1

(s, C6H5), 128.5 (s, C6H5), 128.2 (tv, o/m-C6H5, JPC = 4.8 Hz), 127.3 (s, C6H5), 126.7 (s, C≡CPh),

124.9 (s, C6H5), 109.9 (s, C≡CPh), 82.2 (s, C≡CH), 77.2 (s, C≡CH), 74.0 (s, C1-C5H4), 72.3,

72.2, 70.5, 70.0 (s x 4, C2-4-C5H4), 64.4 (s, C1-C5H4) ppm. 31P{1H} NMR (d6-acetone): 35.5

(s, PPh3) ppm. MS (ES +ve) m/z (abundance) = 1149 (6) [M+K]+. Anal. Calcd. for

C66H50FeO3P2Ru (MW = 1109.96): C 71.4, H 4.5%. Found: C 71.3, H 4.4%.

Figure S1-22. 31P{1H} NMR spectrum of compound 8 in d6-acetone.

Figure S1-23. 1H NMR spectrum of compound 8 in d6-acetone.

Figure S1-24. 13C{1H} NMR spectrum of compound 8 in CD2Cl2.


[Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡CAuPPh3)(CO)(PPh3)2] (9)

[Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡CH)(CO)(PPh3)2] (50 mg, 0.045 mmol) was

dissolved in dichloromethane (20 mL) and [AuCl(PPh3)] (22 mg, 0.045 mmol) and a few drops

of 1,8-diazabicyclo[5.4.0]undec-7-ene (DBU) were added. The mixture was stirred in the dark

for 18 hours after which time ethanol (20 mL) was added and the product obtained as a pale

yellow solid by rotary evaporation. This was washed with cold ethanol (10 mL) and n-hexane

(10 mL) and dried under vacuum. Yield: 37 mg (52%). The product is partially soluble in

ethanol and a second crop could be obtained on further evaporation of solvent. IR: 2182 (C≡C),

1920 (CO), 1593, 1500 (OCO), 1435, 1095, 1027, 813 cm-1. 1H NMR (d6-acetone): 3.26,

3.76, 3.94, 4.1 (s x 4, 4 x 2H, C5H4), 5.63 (s(br), 1H, H), 6.92 (t, 1H, p-CC6H5, JHH = 7.3 Hz),

7.06 (m, 4H, CC6H5), 7.28 - 7.26 (m, 18H, PC6H5), 7.51 (m, 3H, CC6H5), 7.55 - 7.67 (m, 28H,

PC6H5), 7.81 (m, 2H, CC6H5) ppm. 31P{1H} NMR (d6-acetone): 35.3 (s, RuPPh3), 42.0 (s,

AuPPh3) ppm. MS (MALDI +ve) m/z (abundance) = 1306 (11) [M–PPh3]+. Anal. Calcd. for

C84H64AuFeO3P3Ru (MW = 1568.21): C 64.3, H 4.1%. Found: C 64.4, H 4.0%.

Figure S1-26. 31P{1H} NMR spectrum of compound 9 in d6-acetone.

Figure S1-27. 1H NMR spectrum of compound 9 in d6-acetone.


[Ru{C(C≡CPh)=CHPh}(O2CC5H4FeC5H4C≡C)(CO)(PPh3)2]2(Au2dppf) (10)

Compound 8 (50 mg, 0.045 mmol) and [dppf(AuCl)2] (23 mg, 0.023 mmol) were dissolved in

dichloromethane (20 mL). To this was added a few drops of 1,8-diazabicyclo[5.4.0]undec-7-

ene (DBU) and the reaction was stirred in the dark at room temperature for 18 hours. Ethanol

(20 mL) was then added and the solvent volume reduced to provide a pale yellow solid. This

was washed with cold ethanol (10 mL) and n-hexane (10 mL) and dried under vacuum. Yield:

40 mg (56%). IR (solid state): 2160 (C≡C), 1921 (CO), 1594, 1500 (OCO), 1482, 1435, 1094

cm-1. 1H NMR (CD2Cl2): 3.22 (s, 4H, C5H4), 3.87, 3.98, 4.15 (t x 3, 3 x 4H, C5H4, JHH = 1.7

Hz), 4.32, 4.80 (s x 2, 2 x 4H, C5H4), 5.58 (s(br), 1H H), 6.97 (m, 6H, CC6H5), 7.08 (m, 4H,

CC6H5), 7.26 - 7.38 (m, 40H, PC6H5), 7.46 – 7.67 (m, 50H, PC6H5 + CC6H5) ppm. 31P{1H} NMR

(CD2Cl2): 35.7 (s, RuPPh3), 36.6 (s, Au-dppf) ppm. MS (MALDI +ve) m/z (abundance) =

2642 (8) [M–2PPh3]+, 2462 (15) [M–enynyl–PPh3+Na]+. Anal. Calcd. for

C166H126Au2Fe3O6P6Ru2 (MW = 3166.22): C 63.0, H 4.0%. Found: C 63.0, H 3.9%.


[Ru{C(C≡CPh)=CHPh}{O2CC5H4FeC5H4CH=CH(RuCl(CO)(BTD)(PPh3)2)}(CO)(PPh3)2]

(11)

[Ru{C(C≡CPh)CHPh}(O2CFcC≡CH)(CO)(PPh3)2] (62 mg, 0.056 mmol) was dissolved in

dichloromethane (25 mL) and [RuHCl(CO)(BTD)(PPh3)2] (40 mg, 0.057 mmol) added. The

mixture was stirred for 30 minutes after which time ethanol (25 mL) was added and the product

obtained as a dark red solid by rotary evaporation. This was washed with cold methanol (5

mL), cold ethanol (5 mL) and petroleum ether (10 mL) and dried under vacuum. Yield: 57 mg

(56%). IR (solid state): 2162 (C≡C), 1918 (CO), 1593, 1572, 1500 (OCO), 1481, 1433, 1092

cm-1. 1H NMR (CD2Cl2): 3.08, 3.32, 3.52, 3.86 (s(br) x 4, 4 x 2H, C5H4), 5.41 (d, 1H,

RuCH=CH, JHH = 14.5 Hz), 5.55 (s(br), 1H, RuC(C≡CPh)=CHPh), 6.99 (m, 3H, CC6H5), 7.09

(m, 2H, CC6H5), 7.24 - 7.52 (m, 50H, PC6H5 + PC6H5), 7.55 (m, 2H, BTD), 7.64 (m, 15H, PC6H5

+ PC6H5), 7.85 (d, 1H, RuCH=CH, JHH = 14.5 Hz), 7.96 (s(br), 2H, BTD) ppm. 31P{1H} NMR

(CD2Cl2): 26.9 (s, vinyl-RuPPh3), 35.4 (s, enynyl-RuPPh3) ppm. MS (MALDI +ve) m/z

(abundance) = 1801 (7) [M–BTD+H]+, 1538 (11) [M–BTD–PPh3]+. Anal. Calcd. for

C109H85ClFeN2O4P4Ru2S (MW = 1936.25): C 67.6, H 4.4, N 1.5%. Found: C 67.7, H 4.6, N

1.6%.


[Ru{C(C≡CPh)=CHPh}{O2CC5H4FeC5H4CH=CH(OsCl(CO)(BTD)(PPh3)2)}(CO)(PPh3)2]

(12)

[Ru{C(C≡CPh)CHPh}(O2CFcC≡CH)(CO)(PPh3)2] (61 mg, 0.055 mmol) was dissolved in

dichloromethane (25 mL) and [OsHCl(CO)(BTD)(PPh3)2] (48 mg, 0.052 mmol) was added.

The reaction was stirred for one hour after which time ethanol (20 mL) was added and a dark

purple solid was obtained on reduction of the solvent volume (rotary evaporation). This was

washed with cold ethanol (10 mL) and petroleum ether (10 mL) and dried under vacuum. Yield:

60 mg (54%). IR: 1921 (RuC≡O), 1898 (sh, OsC≡O), 1594, 1573, 1503 (OCO), 1482, 1434, 1395,

1093 cm-1. 1H NMR (CD2Cl2): 3.08, 3.28, 3.63, 3.88 (s x 4, 4 x 2H, C5H4), 5.55 (s, 1H,

RuC=CH), 5.61 (d, 1H, OsC=CH, JHH = 16.8 Hz), 6.99 - 7.66 (m, 70H + 2H, C6H5 + BTD), 8.08

(m, 2H, BTD), 8.48 (d, 1H, OsCH, JHH = 16.8 Hz) ppm. 31P{1H} NMR (CD2Cl2): -3.1 (s,

OsPPh3), 35.4 (s, RuPPh3) ppm. MS (MALDI +ve) m/z (abundance): 1890 (5) [M–BTD]+, 1524

(8) [M–2PPh3+Na]+. Anal. Calcd. for C109H85ClFeN2O4OsP4RuS (MW = 2025.41): C 64.6, H

4.2, N 1.4%. Found: C 64.7, H 4.4, N 1.5%.


S2. Crystallography

The X-ray crystal structure of 3·2BPh4

Crystal data for 3·2BPh4: [C112H94N2O4P8Ru2](C24H20B)2·5CHCl2, M = 3044.83, monoclinic,

P21/c (no. 14), a = 11.3803(4), b = 21.7537(9), c = 30.4002(14) Å, β = 92.572(4)°, V =

7518.4(5) Å3, Z = 2 [Ci symmetry], Dc = 1.345 g cm–3, μ(Mo-Kα) = 0.519 mm–1, T = 173 K,

yellow blocky needles, Agilent Xcalibur 3 E diffractometer; 15010 independent measured

reflections (Rint = 0.0412), F2 refinement,S10,S11 R1(obs) = 0.1000, wR2(all) = 0.1925, 10657

independent observed absorption-corrected reflections [|Fo| > 4σ(|Fo|), completeness to

θfull(25.2°) = 98.8%], 886 parameters. CCDC 1840500.

The di-ruthenium complex in the structure of 3·2BPh4 sits across a centre of symmetry at

the middle of the C6–C6A bond linking the two pyridyl rings. The asymmetric unit was found

to contain three distinct sites occupied by dichloromethane solvent molecules, but inspection

of their thermal parameters showed the sites to be only partially occupied, something that was

unsurprising given that the crystal was seen to partially desolvate on the slide before mounting.

When refined freely the occupancies of the C100-, C110-, and C120-based dichloromethane

molecules settled to ca. 0.85, 0.88 and 0.77 respectively, and so for simplicity the combined

occupancy was subsequently set to total exactly 2.5 molecules per asymmetric unit (i.e. 5 per

metal complex). All of the non-hydrogen atoms across all three molecules were refined

anisotropically.

Figure S2-1. The structure of the Ci-symmetric complex present in the crystal of 3·2BPh4

(50% probability ellipsoids).

S3. Photophysics

Absorption spectra were recorded at room temperature using a Perkin Elmer Lambda

35 UV-vis spectrometer. Uncorrected steady-state emission and excitation spectra were

recorded on an Edinburgh FLSP920 spectrometer equipped with a 450 W xenon arc lamp,

double excitation and single emission monochromators, and a Peltier-cooled Hamamatsu

R928P photomultiplier tube (185−850 nm). Emission and excitation spectra were acquired

with a cut-off filter (395 nm) and corrected for source intensity (lamp and grating) and emission

spectral response (detector and grating) by a calibration curve supplied with the instrument.

The wavelengths for the emission and excitation spectra were determined using the

absorption maxima of the MLCT transition bands (emission spectra) and at the maxima of the

emission bands (excitation spectra). Quantum yields (Φ) were determined using the optically

dilute method by Crosby and DemasS12 at an excitation wavelength obtained from absorption

spectra on a wavelength scale [nm] and compared to the reference emitter by the following

equation:S13

where A is the absorbance at the excitation wavelength (λ), I is the intensity of the excitation

light at the excitation wavelength (λ), n is the refractive index of the solvent, D is the integrated

intensity of the luminescence, and Φ is the quantum yield. The subscripts r and s refer to the

reference and the sample, respectively. A stock solution with an absorbance > 0.1 was

prepared, then two dilutions were obtained with dilution factors of 20 and 10, resulting in

absorbances of about 0.02 and 0.08 respectively. The Beer-Lambert law was assumed to

remain linear at the concentrations of the solutions. The degassed measurements were

obtained after passing a stream of argon through the solutions for 10 minutes using a septa-

sealed quartz cell. An air-equilibrated [Ru(bpy)3]Cl2/H2O solution (Φ = 0.028)S14 was used as

the reference. The quantum yield determinations were performed at identical excitation

wavelengths for the sample and the reference, therefore deleting the I(λr)/I(λs) term in the

equation. Emission lifetimes (τ) were determined with the single photon counting technique

(TCSPC) with the same Edinburgh FLSP920 spectrometer using pulsed picosecond LED

(EPLED 360, FWHM < 800ps) as the excitation source, with repetition rates between 1 kHz

and 1 MHz, and the above-mentioned R928P PMT as detector. The goodness of fit was

assessed by minimizing the reduced χ2 function and by visual inspection of the weighted

residuals. To record the 77 K luminescence spectra, the samples were put in quartz tubes (2

mm diameter) and inserted in a special quartz Dewar filled with liquid nitrogen. The solvent

used in the preparation of the solutions for the photophysical investigations was of

spectrometric grade. Experimental uncertainties are estimated to be ±8% for lifetime

determinations, ±20% for quantum yields, and ±2 nm and ±5 nm for absorption and emission

peaks, respectively.

Figure S3-1. Excitation profile of compound 4 in an oxygenated solution of CH3CN (10-5M).

Figure S3-2. Emission profile of compound 4 in an oxygenated solution (red trace) and

deoxygenated solution (blue trace) of CH3CN (10-5 M).

Figure S3-3. Excitation profile of compound 7 in an oxygenated solution of CH3CN (10-5 M).

Figure S3-4. Emission profile of compound 7 in an oxygenated solution (red trace) and

deoxygenated solution (blue trace) of CH3CN (10-5 M).

S4. Electrochemistry

Electrochemical measurements were obtained on a Gamry Reference 600TM (Gamry

Instruments, Warminter, PA, USA) using a standard three-electrode cell with a glassy carbon

disk working electrode (3 mm diameter), Pt wire counter electrode and a Pt wire

pseudoreference electrode. The analyte was dissolved in a 0.1 M solution of NBu4PF6 in

CH2Cl2 and purged with argon prior to, and between scans. At the end of each experiment,

ferrocene was added as an internal standard. The values reported herein are relative to the

Fc/Fc+ couple and corrected for solution resistance (Rs) using Rs values obtained from ac

impedance spectroscopy. NBu4PF6 was obtained from Fluorochem and ferrocene was

obtained from Tokyo Chemical Industry. Both were used as received.

Figure S4-1: The scan rate dependent cyclic voltammogram of 8

Figure S4-2: Plots of ipa (top, blue) and ipc (bottom, orange) vs the square root of the scan

rate for the two redox processes of 8 in figure S4-1.

Figure S4-3: The scan-rate dependent voltammogram of 10

Figure S4-4: Plots of ipa (top, blue) and ipc (bottom, orange) vs the square root of the scan

rate for the two redox processes of 10 in figure S4-3.

Figure S4-5: The CV of 10 showing decomposition of the material after scanning to higher

potentials. The second cycle of the scan (orange) shows a loss of the signal at around 0.2 V

(blue) and a shift in the signal at around 0.6 V (blue) to around 0.8 V.

S5. References

S1 B. P. Sullivan, T. J. Meyer, Inorg. Chem., 1982, 21, 1037-1040; b) A. Keller, B.

Jasionka, T. Glowiak, A. Ershov, R. Matusiak, Inorg. Chim. Acta, 2003, 344, 49-60.

S2 A. Toscani, C. Marín-Hernández, M. E. Moragues, F. Sancenón, P. Dingwall, N. J.

Brown, R. Martínez-Mañez, A. J. P. White and J. D. E. T. Wilton-Ely, Chem. Eur. J.,

2015, 21, 14529 – 14538

S3 (a) A. F. Hill, R. P. Melling, J. Organomet. Chem., 1990, 396, C22−C24; (b) N. W.

Alcock, A. F. Hill, R. P. Melling, Organometallics, 1991, 10, 3898−3903.

S4 J. M. Smieja, C. P. Kubiak, Inorg. Chem., 2010, 49, 9283–9289.

S5 D. Huber, H. Hubner, P. Gmeiner, J. Med. Chem. 2009, 52, 6860-6870.

S6 The BTD complexes were prepared using the same procedure reported for the BSD

(2,1,3-benzoselenadiazole) analogues, in N.W. Alcock, A. F. Hill and M. S. Roe, J.

Chem. Soc., Dalton Trans., 1990, 1737-1740.

S7 A. F. Hill, J. D. E. T. Wilton-Ely, J. Chem. Soc., Dalton Trans. 1998, 3501-3510.

S8 H. Schmidbaur, A. Wohlleben, F. Wagner, O. Orama, G. Huttner, Chem. Ber., 1977,

110, 1748-1754.

S9 D. T. Hill, G. R. Girard, F. L. McCabe, R. K. Johnson, P. D. Stupik, J. H. Zhang, W. M.

Reiff, D. S. Eggleston, Inorg. Chem., 1989, 28, 3529-3533.

S10 SHELXTL v5.1, Bruker AXS, Madison, WI, 1998.

S11 SHELX-2013, G.M. Sheldrick, Acta Cryst., 2015, C71, 3-8.

S12 G. A. Crosby and J. N. Demas, J. Phys. Chem., 1971, 75, 991-1024.

S13 D. F. Eaton, Pure Appl. Chem., 1988, 60, 1107-1114.

S14 K. Nakamura, Bull. Chem. Soc. Jpn., 1982, 55, 2697–2705.

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