new heterocyclic organophosphorus–sulfur–nitrogen compounds, syntheses and structures

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Z. anorg. allg. Chem. 624 (1998) 1497–1502 Zeitschrift fu ¨ r anorganische und allgemeine Chemie WILEY-VCH Verlag GmbH 1998 New Heterocyclic Organophosphorus–Sulfur–Nitrogen Compounds, Syntheses and Structures Petr Kilia ´n, Pavel Pazdera, Jaromı ´r Marek, Josef Novosad, and Jir ˇı ´ Touz ˇı ´n* Brno/Czech Republic, Masaryk University, Department of Chemistry Received November 4th, 1997, revised March 24th, 1998. Abstract. The new compound C 10 H 6 P(S)[NSi(CH 3 ) 3 ] 2 P(S) (3) which contains a P 2 N 2 heterocycle has been prepared in low yield by partial thermal decomposition of 1-{[N,N- bis(trimethylsilyl)acetamidinium]sulfido}-3-(trimethylsilyl- amino)-1 H,3 H,1 k 5 ,3 k 5 -naphtho[1,8 a,8-cd][1,2,6]thiadiphos- phinine-1,3-dithione [CH 3 C{NHSi(CH 3 ) 3 } 2 ] + [C 10 H 6 P(S) · (NHSiMe 3 )SP(S) 2 ] (2). Reaction of 2 with potassium hydro- xide in acetonitrile gives the completely desilylated product [CH 3 C(NH 2 ) 2 ] + [C 10 H 6 P(S)(NH 2 )SP(S) 2 ] (4). The structures of the new compounds 3 and 4 were elucidated by FTIR and NMR spectroscopy methods and by X-ray structure ana- lyses. Keywords: organophosphorus-sulphur-nitrogen compounds, 1,3-diaza-2 k 5 ,4 k 5 -diphosphetidine-2,4-dithione, 1,3-dithia- 2 k 5 ,4 k 5 -diphosphetane-2,4-dithione, 1-thia-3-aza-2 k 5 ,4 k 5 -di- phosphetidine-2,4-dithione, acetamidinium salt, crystal struc- ture Neue heterocyclische Organophosphor–Schwefel–Stickstoff-Verbindungen, Synthese und Struktur Inhaltsu ¨ bersicht. C 10 H 6 P(S)[NSi(CH 3 ) 3 ] 2 P(S) (3), eine neue Verbindung mit einem P 2 N 2 -Heterocyclus, bildet sich mit 8proz. Ausbeute bei der partiellen thermischen Zersetzung von 1-{[N,N-Bis(trimethylsilyl)acetamidinium]sulfido}-3-(tri- methylsilylamino)-1 H,3 H,1 k 5 ,3 k 5 -naphtho[1,8 a,8-cd][1,2,6]- thiadiphosphinin-1,3-dithion [CH 3 C{NHSi(CH 3 ) 3 } 2 ] + [C 10 H 6 P(S)(NHSiMe 3 )SP(S) 2 ] (2). Die Reaktion von 2 mit Kaliumhydroxid in Acetonitril fu ¨ hrt zum vollsta ¨ ndig desily- lierten Produkt [CH 3 C(NH 2 ) 2 ] + [C 10 H 6 P(S)(NH 2 )SP(S) 2 ] (4). Die FTIR- und NMR-Spektren der neuen Verbindungen 3 und 4 werden angegeben und ihre Kristallstrukturen be- schrieben. 1 Introduction Compounds with a P 2 S 2 heterocycle continue to be of great interest since they are widely used as thionation reagents [1] as well as sources of new organophos- phorus compounds [2]. The reaction of P 4 S 10 with excess of 1-bromonaphthalene at 245 °C gave structur- ally interesting derivative 2,4-(naphthalene-1,8-diyl)- 1,3-dithia-2 k 5 ,4 k 5 -diphosphetane-2,4-dithione (1) in moderate yield [3, 4]. Its X-ray structure analysis [3] revealed a less common cis configuration of the P=S groups of the molecule; furthermore, it contains a non-planar P 2 S 2 ring with naphthalene-1,8-diyl back- bone bridging the two phosphorus atoms. The pre- sence of the backbone implies the impossibility to split compound 1 into two fragments with only one phosphorus atom, as it is common in reactions of other organyl-1,3-dithia-2 k 5 ,4 k 5 -diphosphetane-2,4- dithiones [2]. Such interesting structural situation prompted us to study the behaviour of 1 and its reac- tion products. As it was published recently, reaction of 1 with excess of 1,1,1,3,3,3-hexamethyldisilazane (HMDS) in acetonitrile at ambient temperature gives the ionic compound 2 in almost quantitative yield [5]. Crude 2, obtained from this reaction, contains about 4 Mol-% of by- product 5 and about 13 Mol-% of co- product N(SiMe 3 ) 3 . Its purification seems to be very difficult because of sensitivity 2 to air moisture, its ex- treme solubility and tendency to create oversaturated solutions. The structure of 2 was unambiguously * Correspondence Address: Doc. Dr. Jir ˇı ´ Touz ˇı ´n Department of Inorganic Chemistry Masaryk University Kotla ´r ˇska ´2 CR-61137 Brno/Czech Republic E-mail: [email protected]

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Z. anorg. allg. Chem. 624 (1998) 1497±1502

Zeitschrift fuÈ r anorganischeund allgemeine Chemie WILEY-VCH Verlag GmbH 1998

New Heterocyclic Organophosphorus±Sulfur±Nitrogen Compounds,Syntheses and Structures

Petr KiliaÂn, Pavel Pazdera, JaromõÂr Marek, Josef Novosad, and JirÏõÂ TouzÏõÂn*

Brno/Czech Republic, Masaryk University, Department of Chemistry

Received November 4th, 1997, revised March 24th, 1998.

Abstract. The new compound C10H6P(S)[NSi(CH3)3]2P(S)(3) which contains a P2N2 heterocycle has been preparedin low yield by partial thermal decomposition of 1-{[N,N'-bis(trimethylsilyl)acetamidinium]sulfido}-3-(trimethylsilyl-amino)-1 H,3 H,1 k5,3 k5-naphtho[1,8 a,8-cd][1,2,6]thiadiphos-phinine-1,3-dithione [CH3C{NHSi(CH3)3}2]+[C10H6P(S) ´(NHSiMe3)SP(S)2]± (2). Reaction of 2 with potassium hydro-xide in acetonitrile gives the completely desilylated product[CH3C(NH2)2]+[C10H6P(S)(NH2)SP(S)2]± (4). The structures

of the new compounds 3 and 4 were elucidated by FTIR andNMR spectroscopy methods and by X-ray structure ana-lyses.

Keywords: organophosphorus-sulphur-nitrogen compounds,1,3-diaza-2 k5,4 k5-diphosphetidine-2,4-dithione, 1,3-dithia-2 k5,4 k5-diphosphetane-2,4-dithione, 1-thia-3-aza-2 k5,4 k5-di-phosphetidine-2,4-dithione, acetamidinium salt, crystal struc-ture

Neue heterocyclische Organophosphor±Schwefel±Stickstoff-Verbindungen,Synthese und Struktur

InhaltsuÈ bersicht. C10H6P(S)[NSi(CH3)3]2P(S) (3), eine neueVerbindung mit einem P2N2-Heterocyclus, bildet sich mit8proz. Ausbeute bei der partiellen thermischen Zersetzungvon 1-{[N,N'-Bis(trimethylsilyl)acetamidinium]sulfido}-3-(tri-methylsilylamino)-1 H,3 H,1 k5,3 k5-naphtho[1,8 a,8-cd][1,2,6]-thiadiphosphinin-1,3-dithion [CH3C{NHSi(CH3)3}2]+

[C10H6P(S)(NHSiMe3)SP(S)2]± (2). Die Reaktion von 2 mitKaliumhydroxid in Acetonitril fuÈ hrt zum vollstaÈndig desily-lierten Produkt [CH3C(NH2)2]+[C10H6P(S)(NH2)SP(S)2]±

(4). Die FTIR- und NMR-Spektren der neuen Verbindungen3 und 4 werden angegeben und ihre Kristallstrukturen be-schrieben.

1 Introduction

Compounds with a P2S2 heterocycle continue to be ofgreat interest since they are widely used as thionationreagents [1] as well as sources of new organophos-phorus compounds [2]. The reaction of P4S10 withexcess of 1-bromonaphthalene at 245 °C gave structur-ally interesting derivative 2,4-(naphthalene-1,8-diyl)-1,3-dithia-2 k5,4 k5-diphosphetane-2,4-dithione (1) inmoderate yield [3, 4]. Its X-ray structure analysis [3]revealed a less common cis configuration of the P=S

groups of the molecule; furthermore, it contains anon-planar P2S2 ring with naphthalene-1,8-diyl back-bone bridging the two phosphorus atoms. The pre-sence of the backbone implies the impossibility tosplit compound 1 into two fragments with only onephosphorus atom, as it is common in reactions ofother organyl-1,3-dithia-2 k5,4 k5-diphosphetane-2,4-dithiones [2]. Such interesting structural situationprompted us to study the behaviour of 1 and its reac-tion products. As it was published recently, reaction of1 with excess of 1,1,1,3,3,3-hexamethyldisilazane(HMDS) in acetonitrile at ambient temperature givesthe ionic compound 2 in almost quantitative yield [5].Crude 2, obtained from this reaction, contains about4 Mol-% of by- product 5 and about 13 Mol-% of co-product N(SiMe3)3. Its purification seems to be verydifficult because of sensitivity 2 to air moisture, its ex-treme solubility and tendency to create oversaturatedsolutions. The structure of 2 was unambiguously

* Correspondence Address:

Doc. Dr. JirÏõ TouzÏõÂnDepartment of Inorganic ChemistryMasaryk UniversityKotlaÂrÏska 2CR-61137 Brno/Czech RepublicE-mail: [email protected]

proved by 1 D and 2 D NMR experiments [5]. Now weuse this compound as a starting material for furthersyntheses described here.

2 Results and Discussion

C10H6P(S)[NSi(CH3)3]2P(S) (3). Attempts to purifythe crude compound 2 by removing the volatile co-product tris(trimethylsilyl)amine at higher tempera-ture in vacuo resulted in a partial desulfurationand formation of 2,4-(naphthalene-1,8-diyl)-1,3-bis-(trimethylsilyl)-1,3-diaza-2 k5,4 k5-diphosphetidine-2,4-dithione (3), which sublimed off and has been isolatedin 8% yield (Scheme 1). The residue solid after subli-mation was examined by 31P{1H} NMR spectroscopyand found to be a complex mixture. The 31P{1H}NMR spectrum of the crude sublimate shows twosinglets at 55 and 46 ppm with an intensity ratio of 93to 7%. The first signal springs from compound 3, thesecond one from the co-sublimed by-product 5, whoseidentity was confirmed also by 31P and 1H NMR spec-troscopy. Preparation of 5 by the reaction of 1 withHMDS performed in acetonitrile, its X-ray structureanalysis and spectroscopic characterization (NMR,FTIR) are being published [5]. Compounds 3 and 5were separated by fraction crystallization from di-chloromethane. On the basis of their analogous struc-tures were assigned the 1H and 13C NMR signals ofthe naphthalene part of heterocycle 3, the 1H NMRspectrum of 3 shows except the signals of the naphtha-lene hydrogens also presence of two chemicallyequivalent SiMe3 groups in the molecule. Proposed re-action mechanismis described in Scheme 1, the inter-mediates given in square brackets are unstable at thetemperature used and they undergo a ring-cleavageand a subsequent ring-closure reaction to form thedoubly silylated P2N2 heterocycle. Such formation of 3is presumably accompanied by formation of co-pro-ducts HSSiMe3 and MeC(S)NH2, however their iden-tity was not proved. At least, the SiMe3 groups at thenitrogen atoms make this compound a good inter-mediate for the syntheses of further organophos-phorus sulphur nitrogen compounds.

The crystal structure determination of 3 (Tables 1and 2, Fig. 1) confirms that 2 has undergone a rathercomplicated ring-closure reaction to form a 1,3-bis(trimethylsilyl)-1,3-diaza-2 k5,4 k5-diphosphetidine-2,4-dithione. If the different partial conformation ofthe methyl groups at the two silicon atoms is not ta-ken into consideration the molecule shows a high C2v

pseudo-symmetry, otherwise it is lowered to Ci. Thepositions of both phosphorus atoms P(1) and P(2), thetwo sulphur atoms S(1) and S(2) and the naphthalenecarbon atoms do not deviate significantly from theirleast-squares plane; a maximum of 0.07 AÊ is shown byatom S(2). The atoms N(1) and N(2) have been loca-lized at a distance of 1.16 and 1.15 AÊ above and below

1498 Z. anorg. allg. Chem. 624 (1998)

Fig. 1 Molecular structure of compound 3. The non-hydro-gens atoms are drawn as thermal ellipsoids at 50% probabil-ity level. Hydrogens of both SiMe3 groups omitted forclarity.

Table 1 Details of data collections and structure refine-ments of compounds 3 and 4

3 4

Formula C16H24N2P2S2Si2 C12H15N3P2S4

M 426.61 391.45Colour, habit colourless, rhombic yellow, rectangularCrystal size/mm 0.6 × 0.2 × 0.2 0.6 × 0.6 × 0.1Crystal system monoclinic monoclinicSpace group Cc P21/ca/AÊ 11.141(2) 8.720(2)b/AÊ 14.491(2) 17.127(2)c/AÊ 13.519(2) 11.575(2)b/° 91.97(3) 108.60(2)Centered reflections (x) 30 272 h 20.1±25.6 15.5±25.4V/AÊ 3 2181.3(6) 1638.4(5)Z 4 4Dc/Mgm±3 1.299 1.587l/mm±1 0.503 0.770F(000) 896 808Index ranges ±12 ≤ h ≤ 13,

0 ≤ k ≤ 17,0 ≤ l ≤ 16

0 ≤ h ≤ 10,0 ≤ k ≤ 20,±13 ≤ l ≤ 13

Number of measuredreflections

1968 3105

Number of independentreflections (Rint)

1968 2904 (0.0644)

Data/parameters 1968/217 2904/250q, ra) 0.0778, 0.3160 0.0744, 4.3541S on F2 b) 1.022 0.974Final R [I > 2r(I)]c) R1 = 0.0365,

wR2 = 0.0948R1 = 0.0461,wR2 = 0.1180

R (all data)c) R1 = 0.0417,wR2 = 0.0998

R1 = 0.0811,wR2 = 0.1374

Maximun height anddeepest hole in finaldifference Fourier map/eAÊ ±3

0.342, ±0.456 0.581, ±0.859

a) for parameters in the weighting scheme see textb) S = {R[w(F2

0 ± F2C)2]/(n±p)}1/2, where n is the number of

reflections and p is the total number of parameters refinedc) wR1 = {R[w(F2

0 ± F2C)2]/R[w(F2

0)2]}1/2

R1 = R||F0| ± |FC||/R|F0|

P. KiliaÂn et al., New Heterocyclic Organophosphorus-Sulfur-Nitrogen Compounds 1499

this plane, respectively. Both nitrogen atoms show tri-gonal pyramidal configuration, however their devia-tions from planarity is rather small [sum of the bondangles: N(1) 353.2°, N(2) 355.3°]. The geometry at thephosphorus atoms may be described as distorted tetra-hedral. The P=S bond lengths 1.914(2) and 1.917(2) AÊ

fit well with these in 1 {1.912(2) and 1.913(2) AÊ , [3]},however they are substantially shortened when com-pared with average value 1.954 AÊ of a large numberof compounds containing S=P±C moiety found inCambridge Structure Database (CSD) [6]. 80% of theP±N and N±Si bond lengths in large number of com-pounds containing N±P±C and NSiC3 moiety found inCSD [6] were observed in intervals 1.585±1.726 AÊ and1.696±1.783 AÊ , which fit well with P±N and N±Si bondlengths found in 3 (see Table 2).

A comparison of several characteristic structuralparameters of the four-membered rings present in 1,3, 5, 6 and 7 is shown in Table 3. In the series of com-pounds 1, 5 and 3 the four-membered heterocycles aremore and more folded along the P. . . P axis and theendocyclic angles as well as the non-bonding P. . . Pdistances are significantly reduced when the endocyc-lic sulphur atoms are substituted for one or two nitro-gen atoms. Several reports on X-ray structure deter-minations of compounds with a four-membered P2N2

heterocycle showing the atomic sequence C±P(S)±(l-NR)2±P(S)±C (R = e. g. alkyl, aryl) were found inliterature. To our knowledge, however, only two ofthem, i. e. PhP(S)(l-NEt)2P(S)Ph (6) and t-BuP(S)(l-NMe)2P(S)t-Bu (7), show cis-configuration of the P=Sgroups [7, 8]. In contrast to the trans compounds theP2N2 heterocycles in both the cis derivatives arefolded to a greater extend. Whereas the dihedral an-gles at the P. . . P axes of 6 and 7 are found to be 168and 156°, respectively, the corresponding value of thecis compound 3 is 149° only. For its more similar struc-ture, the di-tert-butyl compound 7 ± and not the diphe-nyl compound 6 ± is more suitable for a comparisonwith 3. Whilest the P=S and P±N bond lengths as well

as the N±P±N angles in 3 and 7 are equal within stan-dard deviations, the non-bonding P. . . P distance andP±N±P angles of 3 are slightly reduced (2.42 vs.2.49 AÊ ; 90.5 vs. 93°) ± probably as a result of thenaphthalene-1,8-diyl backbone. The molecules arepacked in layers with the naphthalene rings approach-ing each other face to face and showing an angle ofabout 27° between the naphthalene planes of two ad-jacent items. The closest non-bonding intermolecularS. . . S distance of 3.66 AÊ is found between the atomsS(1) and S(2).

[CH3C(NH2)2]+[C10H6P(S)(NH2)SP(S)2]± (4). Treat-ing of solution of compound 2 in acetonitrile withpowdered potassium hydroxide leads to the formationof the completely desilylated air-stable product 4 in agood yield. The reaction has been performed understrict exclusion of water and therefore we assume theformation of co-products shown in Scheme 1.

Since the potassium salt of acetonitrile KCH2CNwhich had precipitated together with the solid product4 is expected to give acetonitrile and potassium hydro-xide while washing the residue with water, its forma-tion can be proven indirectly. To do so, the originalcrude suspension in acetonitrile was filtered off andthe solid obtained in this way was dried in vacuo inorder to remove the remaining solvent. When thisproduct was dissolved in undried [D6]DMSO the1H NMR spectrum showed the intensive singlet ofacetonitrile, stemming from the reaction of KCH2CNwith water.

Unambiguous identification of two reaction pro-ducts (4 and KCH2CN) led us to assumption that thenext two products are both volatile hexamethyldisil-oxane and trimethylsilylacetonitrile. Their formationwas not proved directly, however the 1H NMR spec-trum of the acetonitrile solution of crude product ob-tained after preceding removing of the solvent in va-cuo (before filtration) as well as mentioned solutionin [D6]DMSO showed presence of no SiMe3 hydro-gens, confirming removability of the products contain-ing these groups in vacuo.

1H, 31P{1H} and 13C{1H} NMR signals of 4 havebeen assigned on the basis of their analogy with 2,

Table 2 Selected bond lengths/AÊ and angles/° of compound 3

P(1)±N(1) 1.703(3) P(1)±N(2) 1.704(4)P(2)±N(1) 1.707(3) P(2)±N(2) 1.699(3)S(1)±P(1) 1.914(2) S(2)±P(2) 1.917(2)P(1)±C(1) 1.787(4) P(2)±C(9) 1.790(4)Si(1)±N(1) 1.769(4) Si(2)±N(2) 1.769(4)

P(1)±N(1)±P(2) 90.5(2) P(1)±N(2)±P(2) 90.7(2)N(1)±P(1)±N(2) 85.5(2) N(1)±P(2)±N(2) 85.5(2)N(1)±P(1)±S(1) 123.3(2) N(2)±P(1)±S(1) 122.0(2)N(1)±P(2)±S(2) 122.0(2) N(2)±P(2)±S(2) 123.6(2)C(1)±P(1)±S(1) 116.0(2) C(9)±P(2)±S(2) 116.1(2)N(1)±P(1)±C(1) 101.8(2) N(2)±P(1)±C(1) 102.5(2)N(1)±P(2)±C(9) 102.3(2) N(2)±P(2)±C(9) 101.5(2)P(1)±N(1)±Si(1) 131.9(2) P(1)±N(2)±Si(2) 131.6(2)P(2)±N(1)±Si(1) 130.8(2) P(2)±N(2)±Si(2) 133.0(2)

Sum of the bond angles:N(1) 353.2 N(2) 355.3

Table 3 Characteristic structural parameters/AÊ , ° of four-membered rings in 3, 1 [3], 5 [5], 6 [7] and 7 [8]

1 5 3 6 7

four-memberedheterocycle

P2S2 P2NS P2N2 P2N2 P2N2

dihedral angle alongthe P. . . P axis

139 146 149 168 156

P. . . P distance 2.73 2.54 2.42 2.49 2.49

endocyclicP±S±P angle

80.0(1) 73.55(4) ± ± ±

endocyclicP±N±P angle

± 97.9(1) 90.5(2) and90.7(2)

2 ×95.0 92.6 and93.4

Scheme 1

where unambiguous assignment had been performedusing 2 D NMR techniques [5]. Substitution of theSiMe3 group in the anion of 2 for hydrogen in 4 re-sults in a slight downfield shift of the NMR signal ofthe phosphorus atom P(2) (57.1 vs. 60.1 ppm).

The X-ray structure analysis of compound 4 (Tab-les 1 and 4, Fig. 2) confirms its ionic character as wellas the absence of any SiMe3 group in either its anio-nic or cationic part. The usually almost planarnaphthalene part of the anion is significantly dis-torted, atom C(9) shows a maximum deviation of0.12 AÊ from the corresponding least-squares plane.The phosphorus atoms P(1) and P(2) are found at dis-tances of 0.53 AÊ above and below that plane which

1500 Z. anorg. allg. Chem. 624 (1998)

Fig. 2 Ionic structure of compound 4. The non-hydrogenatoms are drawn as thermal ellipsoids at 50% probabilitylevel. Symmetry operation ±x + 1, y ± 1/2, ±z + 1/2 could beused for generation of closest anion.

Table 4 Selected bond lengths/AÊ and angles/° of com-pound 4

S(12)±P(1) 2.125(2) S(12)±P(2) 2.085(2)S(1)±P(1) 1.974(2) S(1')±P(1) 1.981(2)S(2)±P(2) 1.956(2) N(1)±P(2) 1.630(4)P(1)±C(1) 1.820(4) P(2)±C(9) 1.814(4)N(2)±C(12) 1.311(6) N(3)±C(12) 1.297(6)C(11)±C(12) 1.482(7)N(1)±H(11) 0.77(6) N(1)±H(12) 0.86(8)N(2)±H(21) 0.83(6) N(2)±H(22) 0.96(5)N(3)±H(31) 0.77(8) N(3)±H(32) 0.79(6)

P(1)±S(12)±P(2) 98.72(6)S(1)±P(1)±S(12) 105.17(7) S(1')±P(1)±S(12) 110.50(6)S(2)±P(2)±S(12) 106.81(7) N(1)±P(2)±S(12) 112.9(2)S(1)±P(1)±S(1') 116.41(7) N(1)±P(2)±S(2) 110.2(2)C(1)±P(1)±S(12) 100.2(2) C(9)±P(2)±S(12) 106.9(2)C(1)±P(1)±S(1) 112.9(2) C(1)±P(1)±S(1') 110.3(2)C(9)±P(2)±N(1) 106.4(2) C(9)±P(2)±S(2) 113.7(2)N(2)±C(12)±C(11) 118.5(5) N(3)±C(12)±C(11) 119.7(5)N(3)±C(12)±N(2) 121.8(4)

Sum of the bond angles:N(1) 359.4 N(2) 359.8 N(3) 359.7 C(12) 360.0

Hydrogen bond S. . . H±N (intraionic):

S . . . H S. . . N S. . . H±N

S(1') . . . H(12)±N(1) 2.65(8) 3.265(5) 130(7)

Hydrogen bonds S. . . H±N (interionic):

S . . . H S. . . N S. . . H±N

S(1)#2 . . . H(11)#1±N(1)#1 2.97(6) 3.649(4) 148(5)S(12)#2 . . . H(12)#1±N(1)#1 2.90(8) 3.554(4) 134(7)S(1')#3 . . . H(21)#1±N(2)#1 2.86(5) 3.371(5) 121(4)S(1')#4 . . . H(22)#1±N(2)#1 2.48(5) 3.413(5) 163(4)S(2)#5 . . . H(31)#1±N(3)#1 2.70(8) 3.441(5) 163(8)S(1)#3 . . . H(32)#1±N(3)#1 2.86(6) 3.596(5) 156(5)

Symmetry transformations used to generate equivalent atoms:

#1 x, y, z #4 ±x + 1, y ± 1/2, ±z + 1/2#2 x, ±y + 3/2, z + 1/2 #5 ±x, ±y + 1, ±z#3 x, ±y + 3/2, z ± 1/2

P. KiliaÂn et al., New Heterocyclic Organophosphorus-Sulfur-Nitrogen Compounds 1501

are more than twice the values of structurally relativeionic compound 8, recently prepared by the reactionof 1 with HMDS in dichloromethane, whose anion isdifferent only by the presence of SiMe3 group bondedto nitrogen [5]. The atoms S(2) and S(12) in 4 areplaced on one side of the naphthalene least-squaresplane, the atoms S(1'), N(1) and surprisingly also S(1),on the other side. The phosphorus atoms show adistorted tetrahedral geometry. As expected, openingof the P2S2 ring results in a substantial lengtheningof the P. . . P distance from 2.73 in 1 [3] to 3.19 AÊ

in 4 and a widening of P±S±P angle from 80.0(1)°to 98.72(6)°; with respect to these values thecompounds 4 and 8 {3.22 AÊ , 100.44(6)°, [5]} matchvery well. The equivalence of both the bond lengthsP(1)±S(1) {1.974(2) AÊ } and P(1)±S(1') {1.981(2) AÊ } canbe interpreted in terms of a delocalization of theminus charge within the PS2 group. The P(2)=S(2)bond length 1.956(2) fit well with average value ofP=S bond distance 1.954 AÊ of a large number of com-pounds containing S=P±C moiety found in CambridgeStructure Database (CSD) [6] and is substantial-ly lengthened when compared with P(1)±S(1){1.914(2) AÊ } and P(2)±S(2) {1.917(2) AÊ } bond dis-tances in 3. In anion of 8 the corresponding P=S bondlength 1.942(1) AÊ has been found. The shortening ofP±N distance in 4 vs. 3 {1.630(4) AÊ vs. 1.699(3) and1.707(3) AÊ } can be interpreted in terms of opening ofsterically hindered four membered P2N2 heterocycle.

The geometry of carbon C(12) in acetamidiniumcation in 4 is planar (sum of the bond angles 360.0°),as well as it was found in several reports on X-raycharacterization of acetamidinium cation with variousanions found in CSD [6].

Intraionic and interionic N±H . . . S bonds in thestructure of compound 4 are listed in Table 4 and de-picted in the Fig. 3. An intraionic N±H . . . S hydrogenbond connects the hydrogen H(12) with sulfur atomS(1') {2.65(8) AÊ }. Weak interionic N±H . . . S hydrogenbridges join both the NH2 hydrogens of one anionwith the atoms S(1) {2.97(6) AÊ } and S(12) {2.90(8) AÊ }of adjacent one to form six membered NH2S2P ring.Using all of its NH2 hydrogen atoms for interionicN±H . . . S bonds the acetamidinium cation is bound tothe sulphur atoms S(1) {2.86(6) AÊ }, S(1') {2.48(5) AÊ ;2.86(5) AÊ } and S(2) {2.70(8) AÊ } of three neighbouringanions. Similar N±H . . . S hydrogen bonds betweencations and anions and also between adjacent anionswere found in structurally relative compound acetami-dinium N-acetimidoyl dithiocarbamate (9) [9]. Themost closest cation-anion H . . . S bonding distance inthe structure of 9 was found to be 2.47(3) AÊ , with cor-responding N±H . . . S angle 173°; which match wellwith the H . . . S distance observed in the structure of 4{2.48(5) AÊ }, whilest the N±H . . . S angles of two stron-gest hydrogen bonds in the structure of 4 are less line-ar (163°). The average value 2.72 AÊ calculated from

four cation-anion S. . . H bond distances observed inthe structure of 4 is significantly higher than averagevalue 2.60 AÊ calculated from three correspondingS. . . H distances observed in the structure of 9. Theanion-anion H . . . S distances {2.90(8), 2.97(6) AÊ } in 4are longer than those in 9 {2.74(3), 2.85(3) AÊ }.

The shortest non-bonded interionic S. . . S distancein 4 is 3.64 AÊ {S(1') . . . S(2)}.

3 Experimental

If not stated otherwise all experiments were performed un-der dry nitrogen gas in Schlenk vessels. Compound 1 wassynthesized from P4S10 and 1-bromonaphthalene [3, 4], 2 hasbeen obtained subsequently from the reaction of educt 1with HMDS and used without further purification [5]. Ace-tonitrile was dried by reflux with CaH2, distilled and then re-distilled from P4O10. Dichloromethane was distilled fromP4O10 and kept over molecular sieves 4 AÊ . Potassium hydro-xide was analytical grade. NMR spectra were recorded on aBruker Avance DRX-500 spectrometer, d values are given inppm, coupling constants in Hz. In the 1H and 13C NMR ex-periments tetramethylsilane (TMS) was used as an internalstandard, in the 31P NMR experiments 85% H3PO4 as an ex-ternal one. IR spectra were recorded in nujol mulls betweenKBr plates on a Bruker IFS 28 spectrometer. Only inter-preted bands in IR spectra are presented, for their decrip-tion were used abbreviations: vs (very strong), s (strong),w (weak), bs (broad, strong), sh (shoulder). Microanalyses

Fig. 3 Intraionic and interionic N±H . . . S bonds in thestructure of compound 4. Naphthalene hydrogens omittedfor clarity.

were carried out in the Department of Inorganic Chemistry,Palacky University, Olomouc.

X-ray Structure Analyses

Details of data collections and refinements are summarisedin Table 1; reflection intensities were collected using gra-phite-monochromatized MoKα (k = 0.71073 AÊ ) radiation ona KUMA KM-4 four circle j-axis diffractometer equippedwith an Oxford Cryostream Cooler at 150(1) K. The cellparameters have been determined by least-squares refine-ments using diffractometer coordinates of x centered reflec-tions in the range (2 hmin, 2 hmax). Data were collected in a2 h range of 4° to 50° applying x-2 h scan techniques. Threestandard reflections did not show any significant variation inintensity during the measurements. Absorption effects wereignored. Scattering factors, dispersion corrections and atomiclinear absorption coefficients were taken from [10]. Bothstructures were solved using direct methods (SHELXS 86,[11]). Non-hydrogen atoms were refined anisotropically by afull-matrix least-squares procedure based on F2 (programSHELXL 93 [12]) and weights given by w±1 = r2(F2

o) +(qP)2 + rP, where P = (F2

o + 2 F2c)/3. All hydrogen atoms

could be localized in a difference Fourier map and were re-fined isotropically. After the last refinement the maximumvalue of D/s was less than 0.001 for both compounds.

Atomic coordinates, thermal parameters and bond lengthsand angles have been deposited at the Cambridge Crystallo-graphic Data Centre (CCDC) under depositon num-ber 100959.

Preparation of C10H6P(S)[NSi(CH3)3]2P(S) (3)

A sublimation apparatus equipped with an air cooler andcharged with 0.8 g (1.32 mmol) of 2 was evacuated to a pres-sure of 15 Pa and heated to 160 °C for 8 h. The white solidwhich sublimed onto the cold parts of the apparatus was dis-solved and recrystallised from dichloromethane. Crystalssuitable for an X-ray structure analysis have been obtainedfrom acetonitrile.

Yield 46 mg (8.2%), m. p. 191/192 °C

Elemental analysis: C16H24N2P2S2Si2 (426.61 amu); C 44.91 (calc.45.04), H 5.64 (5.67), N 5.89 (6.57), S 14.50 (15.03)%.

NMR spectra (CD2Cl2 solution; for the numbering of atoms seeFig. 1): 31P{1H} d 53.6 (s); 1H d 8.20 (m, 2 H; H2 and H8), 8.09 (m, 2 H;H4 and H6), 7.63 (m, 2 H; H3 and H7), ±0.12 {s, 18 H; 2 Si(CH3)3};13C{1H} d 133.3 {d, 1J(PC) 112; C1 and C9}, 133.0 (s; C4 and C6), 132.9 {t,3J(PC) 11.2; C5}, 131.7 (m; C2 and C8), 129.3 {t, 2J(PC) 9.5; C10}, 125.6(m; C3 and C7), ±0.5 {s; Si(CH3)3}.

IR (cm±1): m(P = S) 637 s.

Preparation of [CH3C(NH2)2]+

[C10H6P(S)(NH2)SP(S)2]± (4)

To a stirred solution of 2 (0.5 g, 0.82 mmol) in acetonitrile(5 ml) was added powdered potassium hydroxide (0.053 g,0.95 mmol) and the stirring was continued for 1 d. Thereaftersolvent and all volatile products were removed in vacuo(15 Pa) at 100 °C. The remaining brown residue was dis-

solved in 5 ml of acetonitrile and the resulting suspensionwas concentrated to 1 ml. After 1 d the yellow solid whichhad precipitated was filtered off through sintered glass,washed carefully (stirring!) with 10 ml of water and dried invacuo. 4 shows a rather low solubility in cold acetonitrile;crystals suitable for an X-ray structure analysis were ob-tained from hot acetonitrile.

Yield 183 mg (56.8%), decomposes above 210 °C.

Elemental analysis: C12H15N3P2S4 (391.45 amu); C 36.42 (calc. 36.82),H 3.78 (3.86), N 10.32 (10.74), S 30.93 (32.76)%.

NMR-spectra (CD3CN solution; for the numbering of atoms seeFig. 2): 31P(1H) d 67.6 (d; P1), 60.1 (d; P2), 2J(PP) 13.0 Hz; 1H d 8.79 and8.70 (for both: m, 2 H; H2 and H8), 8.12 and 7.99 (for both: m, 2 H; H4and H6), 7.67 and 7.58 (for both: m, 2 H; H3 and H7), 7.29 (bs, 4 H;2 NH2 in the cation), 5.23 (bs, 2 H; NH2 in the anion), 2.18 (s, 3 H; CH3 inthe cation); 13C{1H} d 168.9 (s; C12), 18.1 (s; C11), 142.4 to 124.7 carbonatoms of the naphthalene entity.

IR (cm±1): ms + as(NH2) 3379 bs, 3331 bs, 3260 s, 3220 sh, 3149 s,ms + as(N±C+±N) 1677 vs, 1656 sh, d(NH2) 1600 w, 1587 w, 1552 w, t(P=S)671 s, 662 s.

Acknowledgements. This work was supported by the grantNo. VS 96095 of the Department of Education of the CzechRepublic and by grants No. 203/95/1190, 203/96/0111 and203/97/0955 of the Grant Agency of the Czech Republic.Authors are grateful to Prof. Dr. G. Becker, Stuttgart, for hisassistance in preparing the paper.

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