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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
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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
+
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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
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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
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CharacterizationofPalladium Telluride anoparticles
HRTEM imageandEDXofPdxTey
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CharacterizationofPalladium Sulfide anoparticles
HRTEM ImageofPdxSy
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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
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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
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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)
One ring is 5 memberedOther ring is 6 membered
(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
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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
+
Reaction Conditions:
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
Reaction Conditions:
ArBr =1.0 mmolPhB(OH)
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
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Heck Reaction
+
Reaction Conditions:
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
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
K2CO
3, DMF / H
2O, 24h at 100C
Complex 7 / 8 / 9
+R Br (OH)2B R
E: S
4848
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Application in Heck Reaction
Reaction Conditions:
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.
One ring is 5 memberedOther ring is 6 membered
5151
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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
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Ruthenium Complexes:Designing and Characterization
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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
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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
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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
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Mecurry Complexes:Designing and Characterization
5757
Hg(II) comple es:
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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
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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
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Tellurides and Ditelluridescontaining Schiff base functionality
6060
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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
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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
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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
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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.
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Thankyou forThankyou for
youryour
listening!!!listening!!!6767
Ring Opening Polymerization
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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
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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
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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
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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
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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
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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
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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
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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)
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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
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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
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Mechanism of Suzuli Coupling Reaction
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B OHAr'
OH
OH
Mechanism of Suzuli Coupling Reaction
PhBr
PhPd(II)Br
NaOH
NaBrPhPd(II)OH
ArB(OH)2
NaOH
B(OH)4
PhPd(II)Ar
PhArPd(0)
7979
Mechanism of Suzuli Coupling Reaction
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S C p g
8080
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Mechanism ofHeck CouplingReaction
8181
Attack of AcO has been shown on the terminal carbon atom but
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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
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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
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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
Receptivit r el. to13Cat natural abundance: 13.4
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
Receptivit r el. to13Cat natural abundance: 3.15
123TeNMR
125TeNMR
77SeNMR
8484
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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
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, 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
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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
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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