arun-nalco presentation

8/8/2019 Arun-NALCO Presentation

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Chalcogeno (S, Se or Te)-Substituted Compounds:Designing and Applications in Organic Synthesis

and Material Science

Department of ChemistryIndian Institute of Technology

Delhi

DR. ARUN KUMAR

11


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Post Doctoral ResearchPost Doctoral Research

PalladiumPalladium ChalcogenideChalcogenide NanoparticlesNanoparticles: Generation , Isolation and Applications: Generation , Isolation and Applications

ChalcogenoChalcogeno Substituted Liquid Crystalline Materials: Syntheses and ApplicationsSubstituted Liquid Crystalline Materials: Syntheses and Applications

Se and Te Substituted Schiff Bases As Sensors: Syntheses and ApplicationSe and Te Substituted Schiff Bases As Sensors: Syntheses and Application

Ph.D. ResearchPh.D. Research IntroductionIntroduction

ChalcogenatedChalcogenated Schiff Bases:Schiff Bases: Designing and CharacterizationDesigning and Characterization Palladium Complexes:Palladium Complexes: Designing, Characterization and ApplicationsDesigning, Characterization and Applications Platinum Complexes: Designing and CharacterizationPlatinum Complexes: Designing and Characterization

Ruthenium Complexes: Designing and CharacterizationRuthenium Complexes: Designing and Characterization

MercurryMercurry Complexes: Designing and CharacterizationComplexes: Designing and Characterization

TelluridesTellurides andand DitelluridesDitellurides containing Schiff Base Functionalitycontaining Schiff Base Functionality

OUTLAY OF THE PRESENTATION

22


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Post Doctoral Research Work

PalladiumPalladium ChalcogenideChalcogenide NanoparticlesNanoparticles::

Generation , Isolation and ApplicationsGeneration , Isolation and Applications

ChalcogenoChalcogeno Substituted Liquid Crystalline Materials:Substituted Liquid Crystalline Materials:Syntheses and ApplicationsSyntheses and Applications

Se and Te Substituted Schiff Bases As Sensors:Se and Te Substituted Schiff Bases As Sensors:Designing and ApplicationsDesigning and Applications

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Palladium ChalcogenideChalcogenide NanoparticlesNanoparticles::Generation , Isolation and ApplicationsGeneration , Isolation and Applications

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Generally believed that reaction is catalyzed by palladium(0) species.

Uncertainity related with catalytic nature of many Pd-complexes: whethertrue catalytic species or pre-catalysts only.

Several reports regarding the potential of palladacycles for efficient

catalysis of various organic reactions including CC coupling reaction.

Few reports on use ofchalcogenated palladacycles as catalyst precursorsfor Heck coupling.

IntroductionSuzuki-Miyaura cross-coupling reaction: one of the most importantmethods known forsp2sp2 CC coupling.

(OH)2BAr X

Aryl Halide Phenyl Boronic AcidK CO , DMF, H O

ArPalladium Catalyst

+

55


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Use of homogeneous (metal complexes of huge number of ligands)and heterogeneous catalysts (metal oxides, supported catalysts on

zeolites/silica /coal or polymer resins) for catalyzing various organicreactions.

Certain drawbacks of both approaches: Difficulty related with the separation of homogeneous catalysts from

reaction mixture so possibility of contamination of the product with

catalyst. A limitation of lower activity and deactivation of the catalyst in caseof heterogeneous reactions.

A solution for lower activities of heterogeneous catalysts: catalysis bynanoparticles (Nano-Catalysis) due to their large surface area.

Taking into account: The high catalytic activities and air/moisture insensitivity of palladium-complexes of chalcogeno substituted (S, Se or Te)compounds

Large number of other applications of nanoparticles. It was thought worthwhile to synthesize the nanoparticles of

PalladiumChalcogenides and to explore their application in catalysis.66


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NH

Se

OH

N Se

OHEtOH

NaBH

Na PdClCH -CO-CH /H O

NH Se

OH

PdCl

ImineSecondary Amine

Se Ligated Palladacycle

(OH) BAr X

Aryl HalidePhenyl Boronic Acid

K2CO3, DMF, H2O

Pd17

Se15

Nanoparticles

Suzuki-Miyaura C - CCoupling Reacion

Ar +

Palladium Selenide Nanoparticles:Generation and Isolation

77

Chem. Commun., 2010, 46, 5954


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Single Crystal Structure of Se Ligated Palladacycle

Selected bond length ()

Pd(1) (18) 1.973(5);Pd(1)N(1) 2.056(4);

Pd(1) l(1) 2.325(16);Pd(1) (1) 2.528(11).

Selectedbond ngles():(18)Pd(1)N(1) 82.00(19);(18)Pd(1) l(1) 94.93(16);

N(1)Pd(1) (1) 97.62(12);

l(1)Pd(1) (1) 85.61(6);

Geomeryaround d:

Square lanar

88

Chem. Commun., 2010, 46, 5954


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Energy (keV)

Counts

151050

5000

4000

3000

2000

1000

0

C

O

Cu

Cu

Cu

Cu

Cu

Pd

Pd

Pd

Pd

Pd

PdPd

Pd

Si

Si

Se

Se

Se

Se

Se

Se

Acquire EDX

HRTEM Image EDX

of d17Se15 afterAnnealingat 450 C

Charaterizaion

Size: ~10nm

99

Chem. Commun., 2010, 46, 5954


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Powder XR Patter of Pd17 e15.

T e patter as been indexed and peaks wit t e following observed d () val es( kl): 3.32 (310), 3.17 (311), 2.92 (320), 2.81 (321), 2.56 (410), 2.49 (411), 2.42(311), 2.36 (420), 2.30 (430), 2.11 (431), 2.06 (511), 2.03 (440), 1.86 (433), 1.76

(600), 1.71 (532), 1.65 (540), 1.63 (541)1010

Chem. Commun., 2010, 46, 5954


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NH S

OH

PdCl

S Ligated Palladacycle

(OH) BAr X

Aryl HalidePhenyl Boronic Acid

K2

CO3, ,

2O

Palladiu Sulfide

Nanoparticles

Ar

NH Te

OH

Pd

Cl OMe

Te Ligated Palladacycle

Palladiu Telluride

Nanoparticles

K2

CO3, ,

2O

Ar

+

Palladium SulfideandPalladium Telluride anoparticles: Generationand Isolation

1111


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CharacterizationofPalladium Telluride anoparticles

HRTEM imageandEDXofPdxTey

1212


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CharacterizationofPalladium Sulfide anoparticles

HRTEM ImageofPdxSy

1313


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ApplicaionofPalladium Sulfide,Palladium SelenideandPalladium Telluride anoparticles

(1) Application in Nano Catalyis:Nano sized particles of palladium chalcogenides have been explored as highlyefficient catalysts in Suzuki Miyaura CC Coupling reactions. The thermalstability, aerobic and moisture insensitivity are additional advantages of thesenano-particles in the area of catalysis.

(2) Magnetic Properies:These properties are currently under the process of investigation and will bereported soon.

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Chalcogeno Substituted

Liquid Crystalline Materials:Syntheses and Applications

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Se Substituted iquid CrystallineMaterials:

O

O

N

Se

O

C10

H21

OH O

O

N

Se

O

C18

H37OH

O

O

N

Se

O

OC10

H21

OC10

H21

C10

H21OH

1 2

3

Seleno substituted Schiff bases showing Liquid Crystalline Properties

Telluriun and Sulfur analogues of these compound have also beenexplored as liquid crystalline materials.

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CharacterizationbyPolarized Optical Microscopy(POM)

Polarized Optical Micrographs

A (43.9 C) (46.0 C)

D(66.0 C)C(65.6C)

Al yl Chain: C10H21

1717


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Al yl Chain: C18H37

Polarized Optical Micrographs

A (68.6 C) B (72.7 C)

B (97.5 C) C (98.5 C)1818


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Palladium ComplexesofLiquid Crystalline Compounds

O

O

Se

O

C10H21

OH

Na2PdCl

4

O

O

N

Se

O

C10H21

O Pd

Cl

Telluriun and Sulfur analogues of these compound have also beensynthesized.

Absence of liquid crystalline properties in all ofthem.1919

O

O

N

Se

O

C18H37

O PdCl

O

O

N

Se

O

OC10H21

OC10H21

C10H21

O Pd

Cl


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Effect ofLiquid CrystallinePropertiesofCompoundsOnNanoparticlesoftheirPalladium Complexes

O

O

N

Se

O

O PdCl

C18 37O

O

N

Se

O

O PdCl

C10 21

AggregatedNanoparticlesComposition:

Se: 45%

Pd: 55%

MonoDispersedComposition:

Se: 60%Pd: 40%

2020


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Scopeofthe Workand Conclusion

Great interest in the synthesis of noble metal nanoparticles formany decades because of their use in applications such as catalysis,

photonics, electronics, and biomedical sensing.

Dependence of these intriguing properties strongly on the size andshape of the nano-particles.

An important subject of chemical research: controlled synthesis ofnanoparticles with well-defined shape and size.

Many Reports related with the development of synthetic methodsby varying the reaction conditions.

First report: on the influence of lengths of alkyl chains (presenton precursors framework) on Size, Dispersion andComposition of nanoparticles.

Possibility of using these results as a new basis for controlled

synthesis of nanoparticles.2121


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Se and Te Substituted Schiff BasesSe and Te Substituted Schiff Bases

as Sensors:as Sensors:Designing and ApplicationsDesigning and Applications

2222


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2323

OH

NSe

OH

NSe

OH

NTe

OH

NTe

OMe

OMe

Schiff Bases substituted with Se have beendesigned and explored as sensorfor Pd(0)

The color transition is readily visible to thenaked eye as a yellow to red colorchange.

Schiff base substituted with Te have beendesigned and explored as sensorfor Hg(II).


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Ph.D. Research Work

IntroductionIntroduction ChalcogenatedChalcogenated Schiff Bases: Designing and CharacterizationSchiff Bases: Designing and Characterization

Palladium Complexes: Designing, Characterization andPalladium Complexes: Designing, Characterization andApplicationsApplications

Platinum Complexes: Designing and CharacterizationPlatinum Complexes: Designing and Characterization Ruthenium Complexes: Designing and CharacterizationRuthenium Complexes: Designing and Characterization

MercurryMercurry Complexes: Designing and CharacterizationComplexes: Designing and Characterization

TelluridesTellurides andand DitelluridesDitellurides containing Schiff Base Functionalitycontaining Schiff Base Functionality

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Compounds containing S, Se or Te are very much attracive for designingnew catalysts because of strong ligating properties of chalcogen atoms.

Organoselenides, when used as ligands in catalytically active species, offergreat potential in transition metal-catalyzed CC bond forming reactions such

as the palladium-mediated Heck reaction. These catalysts not only rival but, inmost cases, outperform each of their respective phosphorus and sulfuranalogues forsimilarHeck reactions ofaryl bromides

2525Org. Lett., 2004, 6, 2997


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Interest in Te and Se ligands has grown in last decade due to availability ofstandardized synthetic routes and FTNMR forstudying solution behavior.

Hybrid ligands containing S, Se and Te can be easily designed by

chalcogenating Schiff base framework.

Schiff bases are important ligands as their metal complexes can show avariety of catalytic organic reactions.

No detailed comparative study on chalcogenated Schiff bases of mono ketones

or aldehydes has been made

Possibility of significant modification in the known catalytic roles of Schiffbases by the presence of S, Se or Te as a donor site in them . Therefore, suchsystems are worth exploring.

Phosphine b

ased c

ataly

stsar

e often wa

tera

ndair

sensitiv

e.T

her

efor

e,

catalysis under phosphinefree conditions is a challenge of high importance, andPdcomplexes of phosphinefree ligands which have promising catalytic activityforCC coupling reactions are of current interest.

The chalcogenated Schiff bases may deal with this challenge in a better waybecause the chalcogen based catalysts are air stable and also not moisturesensitive.

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Objectives

Design chalcogenated Schiff base ligands containing S, Se or Te donor sites

along with N and O.

Explore the coordination chemistry of the newly designed ligands with Soft/

Hard metallic and organometallic species.

Study the use of Pd(II) complexes in organic synthesis (catalytic CC couplingreactions).

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Chalcogenated Schiff Bases Explored

N(CH2)2 E system N(CH2)3 E system

R

N

OH

Me

E

R

N

OH

MeE

N

RE

REN

REN

OH

Me

REN

OH

Me E:

S

or

Se

or

Te

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Precursors Used in The Syntheses

SNH

SeNH

TeNH OMe

SNH

SeNH

TeNH OMe

O

OH

Me

O

OH

Me

O

OH

Chalcogenated Amines Keones

MethodologyofSyntheses: Amine + Keone SchiffBase+ Water

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Characteization Methods of Schiff Bases

C, H, N Analyses IR Spectrocopy 1H NMR Spectrocopy 13C{1H} NMR Spectroscopy

77Se{1H} NMR Spectroscopy 125Te{1H} NMR Spectroscopy Single Crystal X-Ray Diffraction

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OH

N

CH3

Te

OMe

Te(1)C(16) 2.116(2) Te(1)C(15) 2.160(3) N(1)H(1) 1.770(2)

C(15)Te(1)C(16) 95.15(9)

C(11)

N(1)

C(13) 124.5(2)

Crystal system TriclinicSpace group P1

a 6.3152(5) b 8.7203(7) c 18.3132(14) 85.6160(10) 85.8362(11) 76.6560(10)

Tellurated Schiff Base 125Te{1H) NMR

460.3 ppm125Te{1H} NMR signal :

Appears at a position similar to that ofcorresponding free amine

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Se(1)C(12) 1.914(3)

Se(1)

C(11) 1.956(3) N(1)H 1.53(6)

C(11)Se(1)C(12) 99.5(1)C(7) )N(1) )C(9) 122.0(2)

77Se{1H) NMR 286.6 ppm

Selenated Schiff Base

Crystal system Monoclinic

Space groupP2

(1)/ca 16.474(3) b 6.7098(11) c 14.689(2) 108.084(2)

N

OH

CH3

Se

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SC(16) 1.764(4) SC(15) 1.833(4) NH 1.793(3)

C(16)SC(15) 105.39(18)C(1)NC(14) 121.4(3)

Crystal System MonoclinicSpace group P2(1)/c

a 6.7921(16)b 18.802(5) c 13.883(3)

91.077(4)

Sulphated Schiff Base

SC(Aryl) is shorter than SC(Alkyl)

NS

OH

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N

Me

OH

Te

OMe

L12

N

OH

Te

OMe

L14

1

Special NMR Spectral Features of Tellurated Schiff Bases

N

Me

OH

Te

OMe

L11

N

OH

Te

OMe

L13

N(CH2)

2 Te system N(CH

2)

3 Te system

Deshielded by 52Deshielded by 527272 ppmppm(wth respect to that of ArTe(CH(wth respect to that of ArTe(CH

22))22NHNH

22))

Shielded by 6Shielded by 688 ppmppm(with respect to that of Ar Te(CH(with respect to that of Ar Te(CH

22))22NHNH

22))

Remains almost unchanged.Remains almost unchanged.

Remains almost unchangedRemains almost unchanged

125125Te{Te{11H}H}NMR signalNMR signal

TeCHTeCH22

carbon signalcarbon signal 3535


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Palladium Complexes:Designing, Characterization and Applications

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Molecular Structure ofPalladium Complexes

RN

O

Me

EPd

Cl

REN

O

Me

Pd

Cl

N(CH2)

3 E system N(CH

2)

2 E system

E:

S

or

Se

or

Te

Both the rings areSix membered.

One ring is 5 memberedOther ring is 6 membered

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General Methodology for the Syntheses

REN

O

Me

Pd

Cl

REN

OH

MeNa2PdCl

Acetone/ ater, Roo Te p.

Characteization Methods

C, H, N Analyses IR Spectrocopy

1H NMR Spectrocopy 13C{1H} NMR Spectroscopy 77Se{1H} NMR Spectroscopy 125Te{1H} NMR Spectroscopy Single Crystal X-Ray Diffraction 3838


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Crystal tr ct re of Palla i m Com le of

e c iff ase

P (1) e(1) 2.5025(7)

P (1) C

l(1)2

.293

(2

) P (1)N(1) 1.996(7) P (1)O(1) 2.061 (6)

N(1)P (1) e(1) 89.2(2)Cl(1)P (1) e(1) 88.30(6)N(1)P (1)O(1) 90.0(2)

Cl(1)P (1)O(1) 92.59(16)

Crystal system Ort or ombic

ace gro C2cba 9.7664(3) b 16.1747(6) c 27.8791(9)

O

NCH3

Te OMePd

Cl

125Te{1H) NMR

764.1 ppm

125Te{1H} NMR signal :

Deshielded by 298 ppm withrespect to that of

Schiff base

3939

C t l St t f P ll di C l f


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77

Se{1

H) NMR 273.73 ppm(Shielded by 16.17 ppm incomparison to free ligand)

N

OPd

Cl

Se

Square planar geometry at Pd (II)

Pd(1)Se(1) 2.392(2) Pd(1)Cl(1) 2.268(3) Pd(1)N(1) 1.979(6)

Pd(1)O(1) 1.987(6)

N(1)Pd(1)Se(1) 94.30(19)Cl(1)Pd(1)Se(1) 86.57(7)N(1)Pd(1)O(1) 88.4(3)Cl(1)Pd(1)O(1) 90.83(18)

Crystal system TriclinicSpace group P1

a 11.917(9) b 12.161(8) c 15.542(11)

89

.004

(13

) 84.589(14) 62.430(12)

4040

Crystal Structure ofPalladium Complex of

Se Schiff Base

C t l t t f P ll i C l f


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Square planar geometry at Pd (II)

Pd(1)S(1) 2.266(4) Pd(1)Cl(1) 2.309(4) Pd(1)N(1) 2.015(10) Pd(1)O(1) 1.998(8)

N(1)Pd(1)S(1) 97.5(3)Cl(1)Pd(1)S(1) 85.67(14)N(1)Pd(1)O(1) 87.5(4)Cl(1)Pd(1)O(1) 89.3(2)

Crystal System MonoclinicSpace group P2 (1)/c

a 16.038(9) b 10.536(6)

c 12.351(7) 110.369(11)

N

O

CH3

Pd

Cl

S

4141

Crystal tr ct re of Palla i m Com le of

c iff ase


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Special NMR Spectral Features ofPalladium(II) complexes:

DisappearanceDisappearance ofof signalsignal ofof OHOH protonproton inin 11HH NMRNMR spectraspectra..

Both the rings areSix membered.

(N(CH2)3E)


(N(CH2)2Esystem)

N

O

E

Pd

Cl

EN

O

Pd

Cl

4242

DeshieldedDeshielded between 298between 298 andand308308 ppmppm

Magnitude ofMagnitude of DeshieldingDeshielding isisbetween 11between 11 andand2424 ppmppm

125125Te{Te{11H}H}NMRNMRsignalsignalE:

eE:

eE: e E: e

DeshieldingDeshielding is of only 7is of only 71111 ppmppmDeshieldedDeshielded by ~150by ~150 pmpm7777Se{Se{11H}H}NMRNMRSignalSignal


43/88

Change in signals of NCH2

and CH2S protons on Complexation

CH2S

NCH2

SPhN

OPd

Cl

SPhN

OH

CH2SNCH2

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Application ofPalladium ComplxesCC Coupling Reaction:

Reaction Conditions:

ArBr =1.0 mmolPhB(OH)

2=1.5 mmol

K2CO

3=2 mmol

DMF =4 mLH

2O = 0.5 mL

Catalyst =0.001 mmolTime =24 h at 100C

Suzuki Reaction

Substituents onReactantants

(R)

Catalyst23 31

Conversion (%)

OMe 10 10

H 40 35

NO2

75 80

R r (OH)2

B

K2CO

3, DMF / H

2O, 24 h at 100C

Palladium Complex

+

Conversion (%) is marginally lowerin comparision to the case ofPd(II)complexes of selenated Schiff bases

at similar reaction conditions

E: Te

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COOH

COOH

COOH

Ph

Ph

Ph

Ar- Y

IO N

ICl

BrO N

IO N

ICl

BrO N

75

5

32

75

75

32

70

0

30

72

70

35

23 31

Conversion (%)

Heck Reaction

Ar XY Y

ArPalladium Complex

Na2CO

3, DMF, N

2atm, 24 h at 100C

+


ArI =1.0 mmolAlkene =1.5 mmolNa

2CO

3=2 mmol

DMF =4 mLCatalyst =0.001 mmolTime =24 h at 100C, N

2atm

Conversion (%) is marginally lowerin comparision to the case ofPd(II)complexes of selenated Schiff basesat similar reaction conditions

E: Te

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R Br (OH)2

B R

K2CO

3, DMF / H

2O, 24 h at 100C

Palladium Complex+

Suzuki Reaction

E: Se

Substituents onReactantants

(R)

Catalyst

15 17 19 21

Conversion (%)

OMe 15 10 20 15

H 40 25 45 30

NO2

85 82 87 84



2=1.5 mmol

K2CO

3=2 mmol

DMF =4 mL

H2O = 0.5 mLCatalyst =0.001 mmolTime =24 h at 100C

Conversion (%) is generally higherin comparision to the case ofPd(II)complexes of sulphated Schiff bases

at similar reaction conditions

4646


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Heck Reaction

+


ArI =1.0 mmolAlkene =1.5 mmolNa

2CO

3=2 mmol

DMF =4 mLCatalyst =0.001 mmolTime =24 h at 100C, N

2atm

OOH

COOH

COOH

Ph

Ph

Ph

Ar-X Y

IO2N

ICl

rO2N

IO2N

ICl

rO2N

80

74

38

78

70

35

85

80

35

83

78

33

15 17

Conversion(%)

72

68

30

70

65

30

74

65

33

78

68

30

19 21

Ar XArPalladium Complex

Na2CO

3, DMF, N

2atm, 24 h at 100C

+

Conversion (%) is generally higherin comparision to the case ofPd(II)complexes of sulphated Schiff basesat similar reaction conditions

E: Se

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Substituents onReactantant

(R)

Conversion (%)

7 8 9

OMe 25 10 30

H 45 20 50

NO2

80 70 80

Suzuki Reaction



2=1.5 mmol

K2CO

3=2 mmol

DMF =4 mLH

2O = 0.5 mL

Catalyst =0.001 mmolTime =24 h at 100C

K2CO

3, DMF / H

2O, 24h at 100C

Complex 7 / 8 / 9

+R Br (OH)2B R

E: S

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Application in Heck Reaction


ArI =1.0 mmolAlkene =1.5 mmol

Na2CO3 =2 mmolDMF =4 mLCatalyst =0.001 mmolTime =24 h at 100C, N

2atm

Ar XY Y

ArPalladium Complex

Na2CO

3, DMF, N

2atm, 24 h at 100C

+

COOH

COOH

COOH

Ph

Ph

Ph

Ar- Y

IO2N

ICl

BrO2N

IO2N

ICl

BrO2N

78

70

35

75

78

30

78

70

25

74

70

28

7 8

Conversion (%)

8

5

25

8

0

32

9

Catalyst

E: S

4949


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Platinum Complexes:Designing and Characterization

5050


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Molecular Structure ofPlatinum Complexes inN(CH

2)

2E System

RN

O

Me

E

Pd

Cl

N(CH2)

2 E system

E:

S

or

Se

or

Te

General Methodology for the Syntheses

REN

O

Me

Pt

Cl

REN

OH

MeK2PtCl4

Acetone/Water, Room Temp.


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Molecular Structure ofPlatinum Complexes inN(CH

2)

3E System

E:

Se

or

Te

E

OH

N

CH3

Pt

Cl

Cl

E

OH

NCH3

Pt

E

Cl

E

OH

N

CH3

OHN

CH3

Cl

Trans Isomer

Cis Isomer

5252


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Ruthenium Complexes:Designing and Characterization

5353


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Methodology of Syntheses of Ru(II) complexes:

Cl

RuRu

ClCl

Cl

OH

N

CH3

Te

OMe

Dichloromethane,RT

CH3

CH3

CH3

Cl

N

Te

OMeCH3

OH

Ru


55/88

25 / 29: R = CH3, R & R = (CH

2)

4

33 / 37: R = Ph, R & R = H

Characterization of Ru(II) complexes:

Further Support: Change in signals of TeCH2

andNCH

2protons after complexation

HRMS: (25) 720.0462 (M+Cl)(29) 734.0619 (M+Cl)(33) 733.0520 (MH+Cl)(37) 746.0614 (M+Cl)

Metal : Ligand Ratio 1 : 1

NCH2 TeCH2

Ligand L13Ru(II)

complex

NTe

OMeOH

CH3

CH3

CH3

Cl

N

Te

OMe

R

OH

R'

R''

Ru

(CH2) Cl

4

9

n = 1 or2

Deshielding (49Deshielding (4975 ppm) of75 ppm) of125125Te{Te{11H} NMRH} NMRsignalsignal

Deshielding (10Deshielding (1011 ppm) of11 ppm) ofCC55 (CH(CH22Te) SignalTe) Signal

Deshielding (6Deshielding (67 ppm)7 ppm)of Cof C44 signalsignal

Shielding (Shielding (~3ppm) of~3ppm) of=NCH=NCH

22signalsignal

CoordinationCoordinationthroughthrough

TeTeandand

NNCC99 carbon signalcarbon signal is Unchangedis UnchangedOH signalOH signal is present inis present in

11HNMR spectra.HNMR spectra.

Not throughNot through

OOn

5555


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=NCH2

TeCH2

NCH2

TeCH2

=NCH2 TeCH2

NCH2+ TeCH2

TeCH2+CH ofi-pr

Ru(II) Complex

TeCH2NCH2

Ru(II) Complex

NCH2 TeCH2 CH ofi-pr

Ru(II) Complex

N

OH

CH3

Te

OMe

L12

N

OH

Te

OMe

L14

N

OH

Te

OMe

CH3

L11

5656


57/88

Mecurry Complexes:Designing and Characterization

5757

Hg(II) comple es:


58/88

TeCH2=NCH2 2.88

N

OH

CH3

Te OMe

L12NCH

2TeCH2 3.28

Hg(II) Complex

Hg(II) complexes:

26 / 30: R = CH3, R& R = (CH

2)

4

34 / 38: R = Ph, R& R = H

MeO

N

(CH2)n

R' R''

OH

R

(CH2)n

Te

Hg

BrBr TeOMe

N

R'R''

OH

R

1

23

4

=NCH2

TeCH2

3.00

N Te

OH

CH3

OMe

Ligand L11

=NCH2 TeCH2

3.50Hg(II) Complex

HRMS: (26) 1179.0170 (M+Br)(30) 1207.0450 (M+Br)

Metal : Ligand Ratio 1 : 2

4

9

9

n = 2or3

n = 2or3

Shielding (85Shielding (85105 ppm) of105 ppm) of125125Te{Te{11H} NMRH} NMRsignalsignal

Deshielding (11Deshielding (1114 ppm) of14 ppm) of

CC55 (CH(CH22Te) SignalTe) SignalDeshielding (1.5Deshielding (1.52.5 ppm)2.5 ppm)

of Cof C44 signalsignal

CoordinationCoordinationthroughthrough

TeTe

=NCH=NCH22

: Unchanged: UnchangedCHCH33 signalsignal :: UnchangedUnchanged (in(in 2626 andand 3030))CC1414 signal : Unchanged (insignal : Unchanged (in 3434 andand 3838))CC99 signal : Unchangedsignal : Unchanged

OH signal : Present inOH signal : Present in11

HNMR spectraHNMR spectra

Not throughNot through

NNandand

OO

5858


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=NCH2TeCH2

N

OH

Te

OMe

2.95

=NCH2

N

OH

Te

OMe

TeCH2

2.83 ppm

=NCH2 TeCH2

3.49

=NCH2

TeCH2 3.22 ppm

Ligand L13

Ligand L14 Hg(II) Complex

Hg(II) Complex

5959


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Tellurides and Ditelluridescontaining Schiff base functionality

6060


61/88

Syntheses of Ditellurides containing Schiff base functionalityand their mono telluride analogues

N

OH

CH3Te

N

OH

CH3

N

OH

CH3

TeN

OH

CH3

N

OH

TeN

OH

TeN

OH

CH3Te

N

OH

CH3

TeN

OH

CH3

TeN

OH

CH3

TeN

OH

TeN

OH

O

OH

CH3

O

OH

CH3

O

OH

Te Te NH2NH2

DryMeOH, r.t.

Te Te NH2NH2

DryMeOH, r.t.

Te Te NH2NH2

DryMeOH, r.t.

TeNH2

NH2

DryMeOH, r.t.

TeNH2

NH2

DryMeOH, r.t.

TeNH2

NH2

DryMeOH, r.t.

Novel DitelluridescontainingSchiffbasefunctionalty

CorrespondingMono-tellurideanalogues

(5)

(1)

(4)

(6)

(2)

(3)

Characterization of1 to 6 has been carried out byproton, carbon13 and tellurium125 NMR spectroscopy

6161

NMR S f Di ll id 2 & di ll id 1


62/88

NMR Spectra of Ditelluride 2 & corresponding telluride 1

1H NMR Spectrum of2 13C{1H} NMR Spectrum of2

67

9

8

1 2

OH

CH3

125Te{1H} NMR 220.84 ppm 97.97 ppm

The 1H and 13C{1H} NMR spectra of 1 and 2 are almost similar except the position ofTeCH

2protons in 1HNMR spectra.

TeCH2

signal in 1HNMR 3.04 ppm 3.36 ppm

OH

N

CH3

Te Te N

CH3

OH

N

CH3

OH

Te

OH

N

CH3

(2)

1 2

3

4

5

6 7

8

9

First Example of Ditelluride containingSchiff Base Functionality

(1)

2

3

4

5

67

8

9

1

Corresponding Monotelluride containingsame Schiff Base Functionality

2

3

5

4

9

7

8

61

CH3

6262


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Significance of Ditellurides containing Schiff base functionality

The borohydride reduction of such compounds can generate firstexamples of (N, O, Te) ligands, which can be reacted further with a

variety of functionalized organic halides to prepare diversemultidentate hybrid organotellurium ligands.

Thus importance of such compounds as precursors in thecontext of furtherance of ligand chemistry of tellurium isimmense.

NaBH4

/ NaOH

Dry C2H

5OH,Reflux

TeNa

(CH2)n

NH

OH

R

Chlorocompoundin C

2H5OH

New Organotellurium Ligand

First Example of intermediatecontaining (O, N, Te) donor sites

N

OH

R

(CH2)n Te Te (CH

2)n N

R

OH

6363

Ligand Exchange Reaction of (2)


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125Te{1H} NMR Spectrum ofEquilibrium Mixture of (2), (2a) and (2b)

2b

2a 2

455.35 287.7 251.8 97.97

DEPT 135 NMR Spectrum ofEquilibrium Mixture of (2), (2a) and (2b)

TeCH2NCH2

OMe

CH3

14.6314.76

3.474.54

52.3452.44

LigandExchangeReactionof(2)

N

CH3

Te

OH

Te

OMe

Te Te

OMeMeO

N

CH3

OH

N

CH3

Te

OH

Te

(2)(2

a)

(2b)

+

Mixing of 2 with 2a in equimolar ratio inCDCl3 leads to the formation of an asymmetricditelluride (2b).

98.0 ppm 457.0 ppm

Spectra are the sum of the contributions from each component of the equilibriummixture.

6464

C l i


65/88

Novel ditellurides containing Schiff base functionality have been designed for the firsttime and their ligand exchange reactions with other ditellurides have been explored.

Monotellurides containing Schiff base functionality have been designed and comparedwith ditellurides containing the same functionality.

Sulphated, Selenated and Tellurated Schiff bases (total 14 in number) have beendesigned and their complexation with Pd(II), Pt(II), Ru(II) and Hg(II) has been carried out.

The complexation of selenated and tellurated Schiff bases with Pt(II) becomes differentwhen value of n in the ligand backbone >C=N(CH

2)nE changes from 2 to 3.

In 77Se{1H} and 125Te{1H} NMR spectra of Pd (II) / Pt(II) complexes, the shift of signalrelative to free ligand depends on the size of chelate ring (5-membered > 6 membered)

Study on the catalytic activity of Pd (II) complexes of (O, N, E)Schiff base ligands forCC coupling reactions (Suzuki and Heck Type) has been made. The advantage of usingthem is that they are air stable and also not moisture sensitive.

The catalytic activity of Pd (II) complexes of tellurated ligand in CC coupling reactions(Suzuki and Heck Type) has been explored first time.

Conclusion

List of PublicationsList of Publications


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List of PublicationsList of PublicationsIn JournalsArun Kumar, Ajai K. Singh, First ditelluride containing Schiff base functionality: synthesis and instantaneous ligandexchange with other ditelluride investigated by 125Te NMR Inorg. Chem. Commun. 10 (2007) 1315.

Arun Kumar, Monika Agarwal and Ajai K Singh, Selenated Schiff bases of 2hydroxyacetophenone and their palladium(II) and platinum(II) complexes: syntheses and crystal structures and applications in Heck reactionPolyhedron 27(2008) 485.

Arun Kumar, Monika Agarwal, Ajai K. Singh, Schiff bases of 1hydroxy2acetonaphthone containing chalcogenfunctionalities and their complexes with and (pcymene)Ru(II), Pd(II), Pt(II) and Hg(II) : synthesis, structures andapplications in CC coupling reactions J. Organomet. Chem. (Accepted).

Arun Kumar, Monika Agarwal, Ajai K. Singh, Palladium(II), platinum(II), ruthenium(II) and mercury(II) complexes ofpotentially tridentate Schiff base ligands of (E, N, O) type (E = S, Se, Te): Synthesis, crystal structures and applicationsin Heck and Suzuki CC coupling reactions Inorg. Chim. Act. (Under Review).

In Conferences / SymposiaArun Kumar, Ajai K. Singh, Secondary interactions in crystals water soluble derivatives of tellurated alkylamines,tellurated Schiff bases and metal complexes of hybrid organotellurium ligands, 11th Symposium on Modern Trends inInorganic Chemistry (MTICXI), held at IIT Delhi, Dec 08-10, 2005.

Arun Kumar, Raghavendra Kumar P., Ajai K. Singh, Multidentate organsulphur and organotellurium ligands and theirmetal complexes: synthesis and structural aspects, OMCA 07 National Symposium on Recent Trends in OrganometallicCompounds and Their Industrial Applications, held at KIIT University Bhubaneswar, Orissa, Feb 2628, 2007.

Arun Kumar, Ajai K. Singh, Polydentate tellurium and selenium ligands and their metal complexes: synthesis andstructural aspects, 12th Symposium on Modern Trends in Inorganic Chemistry (MTICXI), held at IIT Chennai, Dec0608, 2007.

6666


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Thankyou forThankyou for

youryour

listening!!!listening!!!6767

Ring Opening Polymerization


68/88

Asymmetric Enantoselective Conjugate Additionto , unsaturated imide

R R'

O uHR R'

Nu O

( , )-[(salen)Al]2O

NuH HN3, HCN, HSAr, R"CH

2NO

2,

Al

O

NN

OBu-t

t-Bu Bu-t

t-Bu

(S,S)-(salen)Al

O O

O

Catalyst

n

O CH2.CH2.CH2.OC

O

Ring Opening Polymerization

Macromolecules 38 (2005) 5406

6868

Selective Organic Transformations


69/88

Selective Organic Transformations

O2

OH

H

OH

N

OH

N

Hy ro ylatio of Styre e

(R)[CoII(L)]L=

ee: 38.0 %

OH

N

Br

OH

Al ol Co e satio

O

R H

OMe

Me R Me

OOH L=(R)[TiIV(L)(OPri)

2

ee: 66-98 %2N HCl

+

+

6969


70/88

OH

N

N

OHEpo i atio of Alke es

NaClOO

ee: 1315 %

(S)[MnII(L)]L=

Ru

O

NN

O

PP3

PP3

O2N

NO2 O2N

NO2

O NH

OH

O

N

O

O

O

Dehydrogenation plus intramolecular DielsAlder cycloaddition

+

7070

M lti l t R d C t l i


71/88

Multielectron Redox Catalysis

2e, H+2

Oxovanadium acetylacetonate[ VO(acac)

2]

Oxidative Coupling ofAryl Sulfides

SR S

R

SR+

O2

S

R

S S

R

R

++ H+

[VV]

[VIII]

J. Org. Chem.61 (1996) 1912

nS S

R R

[ VO(sale -(NO2)

2)], O

2

CF3

SO3

H, CH2

Cl2

S

Electrophilic Substitutio Reactio of sulfo ium catio sforme bt the multi-electro o i atio of aromatic isulfi e 7171

Kharasch Addition and Enol Ester Synthesis


72/88

Kharasch Addition and Enol Ester Synthesis

O

R OH

R' HO

O

R'

R

O

ORR'

O

OR

R'

Markovnikov anti-Markovnikov [E] anti-Markovnikov [Z]

R'

R

CXCl3

ORu

NR

Cl

R = Me ort-Bu

R'

R

Cl

CXCl2[X = Cl]

Atom ra sfer Ra ical Additio (or KharaschAdditio )

Enol Ester Synthesis

+

+

+

+

7272

Alkene Polymerisation


73/88

Ru

[Ru] [Ru]

H

n

Norbornene Polymerization

Alkene Polymerisation(RingOpening Metathesis)

RingRing--opening metathesis is used as a method of polymerization.opening metathesis is used as a method of polymerization.

Usually, it is applied most often when ring opening creates aUsually, it is applied most often when ring opening creates a

relief of strain, as in some bicyclic alkenes.relief of strain, as in some bicyclic alkenes.

Norbornene Polynorbornene

7373

Ol fi M t th iOl fi M t th i


74/88

Olefin MetathesisOlefin Metathesis

InIn crossedcrossed--olefinolefin metathesis,metathesis, oneone alkenealkene isis convertedconverted toto aa mixturemixtureofof twotwo newnew alkenesalkenes..

2 CH3CH=CH2catal st

CH2=CH2 + CH3CH=CHCH3

TheThe reactionreaction isis reversible,reversible, andand regardlessregardless ofof whetherwhether wewe startstart withwithpropenepropene oror aa 11::11 mixturemixture ofof ethyleneethylene andand 22--butene,butene, thethe samesame

mixturemixture isis obtainedobtained..

The reaction is generally catalyzed a transition metal complex.The reaction is generally catalyzed a transition metal complex.

Typically Ru, W, or Mo are used. Shown below is Grubbs catalyst.Typically Ru, W, or Mo are used. Shown below is Grubbs catalyst.

p-cy

p-cy

CH

Cl

Cl 7474


75/88

Ru CHPh

p-cy

Cl

O

NR'

Dissociation

Association - Olefin

Olefin

Ru CHPh

p-cy

Cl

O

NR'

R"

Ru CHPh

p-cy

Cl

O

NR'

Vacancy

Ru CHPh

ClCl

O

NR'

Ru ClMeMe

- Olefin

Olefin

Ru CHPh

ClCl

O

NR'

Ru ClMe

Me

Ru CHPhCl

O

NR'

Vacancy

Ru CHPhCl

O

NR'

R"

MeMe

RuClCl

MeMe

RuClCl

+

Mechanism of Ring Closing Metathesis (RCM) andRing Opening Metathesis ROMP

7575

Mechanism of Pd(0)Pd(II)


76/88

L

PdL

Br

Oxidative Addition

Pd Br

L

LR

Pd BrL

L

R

InsertionPdR

H

H Br

L

L

R

Pd BrH

L

L

RPd BrH

L

L

Base

HBr / Base

Reductive Elimination

Mechanism ofPd(0) Pd(II)Heck Coupling Reaction

Complex

P

d intermediate

H elimination

Complex

(0)

(II)

(II)

(II)

(II)

7676

Mechanism of Pd(II)Pd(I ) Heck Coupling Reaction


77/88

Mechanism ofPd(II) Pd(I ) Heck Coupling Reaction

Oxidative dditiono h r

aser / ase

R

Pd

Br

Y

Y

AcO

Pd

BrAcO

Pd

BrBr

PhY

oss o cO

YPdBr

Br

Ph

Migration o Ph toterminal carbon

Pd

BrBr

Y

PhBeta ydro gen limination

Y

P

Pd

BrBr

H

Pd

Br

Attack of AcO

(shown on the term inal carbon atombut could be on the internal carbon.

Tetrahedron

63 (2007) 6949

Chem. Eur. J.7 (2001) 1703

7777


78/88

Mechanism of Suzuli Coupling Reaction


79/88

B OHAr'

OH

OH


PhBr

PhPd(II)Br

NaOH

NaBrPhPd(II)OH

ArB(OH)2

NaOH

B(OH)4

PhPd(II)Ar

PhArPd(0)

7979



80/88

S C p g

8080


81/88

Mechanism ofHeck CouplingReaction

8181

Attack of AcO has been shown on the terminal carbon atom but


82/88

Tetrahedron 63(2007)6949Chem. Eur. J. 7(2001)1703

it could be on the internal Carbon.

Mechanism ofHeckReactionPd(II)Pd(IV)

8282

(a) CH2=CHY


83/88

Mechanism ofHeckReactionPd(II)Pd(IV)

Tetrahedron 63(2007)6949

(b) Reversible AttackofAcO: attack isshownon the terminal carbonatom butit couldbeon the internal Carbon.

(c) Oxidative AdditionofArBr(d)ReversibleLossofAcO

(e)MigrationofArtoTerminal Carbon(f) Beta-Hydrogenelimination (g)Removal ofHBrby AcO

8383

Spin: 1/2


84/88

Natural abundance: 0.89%Chemical shift range: 5800 ppm(-1400 to 3400)

requenc ratio: 26.169742%Reference compound: Me

2Te inC

6D

6Receptivit r el. to1Hat natural abundance: 1.64 104

Receptivit r el. to13Cat natural abundance: 0.961

Spin: 1/2Natural abundance: 7.07%

Chemical shift range: 5800 ppm(1400 to 3400)requenc ratio: 31.549769%Reference compound: Me2Te (90%)Receptivit r el. to1Hat natural abundance: 2.28 103


Spin: 1/2Natural abundance: 7.63%Chemical shift range: 3000 ppm (1000 to 2000)

requenc ratio: 19.071513%Reference compound: Me2SeReceptivit r el. to1Hat natural abundance: 5.37 104


123TeNMR

125TeNMR

77SeNMR

8484


85/88

Atomic

Number

Electronic

Configuration

ElectronsperShell

Common Oxidation States of palladium are 0, +1, +2 and +4. Althoughoriginally +3 was thought of as one of the fundamental oxidation states ofpalladium, there is no evidence for palladium occurring in the +3 oxidationstate; this has been investigated via X-Ray diffraction for a number ofcompounds, indicating a dimer of Palladium(II) and palladium (IV) instead.

Recently, compounds with an oxidation state of+6

were synthesised.

2828 4646 7878

[Ar] 3d[Ar] 3d88, 4s, 4s22 [Kr]4d[Kr]4d1010 [Xe][Xe]

4f4f1414 5d5d996s6s112,8,16,22,8,16,2 2,8,18,18, 02,8,18,18, 0 2, 8, 18, 32, 17, 12, 8, 18, 32, 17, 1

Palladium PlatinumNickel

8585

Octahedral, Tetrahedral & SquarePlanarOctahedral, Tetrahedral & SquarePlanar


86/88

, q, q

CF Splitting pattern forCF Splitting pattern forvarious molecular geometryvarious molecular geometry

M

dz2dx2-y2

dxzdxy dyz

M

dx2-y2 dz2

dxzdxy dyz

M

dxz

dz2

dx2-y2

dxy

dyz

OctahedralOctahedral

TetrahedralTetrahedral Square planarSquare planar

Pairing energy s. (

Weak field ( < Pe

Strong field ( > Pe

Small ( J High SpinMostly d8

(Majority Low spin)

Strong field ligands

i.e.,P

d2+

,P

t2+

, Ir+

, Au3+

8686


87/88

3434 5252

[[ArAr] 4s] 4s22

3d3d1010 4p4p44[[KrKr] 5s] 5s22

4d4d1010 5p5p44

2, 8, 18, 62, 8, 18, 6 2, 8, 18, 18, 62, 8, 18, 18, 6

AtomicNumber

ElectronicConfiguration

ElectronsperShell

Selenium Tellurium

8787

Some more functionalized ditellurides


88/88

Phosphorus Sulfur Silicon126(1997) 291

Organometallics15 (1996) 1707

J. Organomet. Chem.437 (1992) 299

TeTe

NMe2

NMe2

OH

Me Te

Te

OH

Me

Te Te

NMe2 Me2N

Fe Fe

arun-nalco presentation

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