organometallic chemistry: synthesis, structure … chemistry: synthesis, structure and applications...
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Organometallic Chemistry: Synthesis, Structure and
Applications of Organochalcogens (S, Se, Te), -mercury
A. Synthetic Metals: Synthesis and structural characterization of organosulfur
-donors and acceptors for structure-property correlation
B. Systematic study of intramolecularly coordinated
organochalcogens (Se, Te):
1. E···D secondary bonding by X-ray and NMR etc.
D
EX
D = N, O
E = O, S, Se, Te
X = E, Halogens, Organyl groups
2. Isolation of novel species which are otherwise unstable, show unusual reactivity
3. Hybrid multidentate ligands containing both “hard” and
“soft” donor atoms: chiral, macrocyclic ligands
4. Synthetic organochalcogens with Glutathione Peroxidase
(GPx)-like activity
5. Monomeric, volatile stoichiometric organometallic precursors for
MOCVD of Group II-VI semiconductors
C. Metal Metal interactions (Hg)
Synthetic metals and Superconductors
1973
TTF.TNCQ First Organic Metal
(TMTSF)2ClO4
First Organic Superconductor
Tc ~ 1 K
(BEDT-TTF)2[Cu{N(CN)2}Cl]
Tc 12.5-12.8 K
S
S S
S
CN
CN
NC
NC
TTF TCNQ
S
S S
SS
SS
S
BEDT-TTF
Se
Se Se
Se
TMTSF
Singh et al.
J. Chem. Soc., Chem. Commun., 1991, 952.
J. Chem. Soc., Perkin Trans I, 1991, 3341.
Chemistry and Industry, Applied Higlights, 1991, P805.
J. Chem. Soc., Perkin Trans I, 1992, 2913.
J. Org. Chem., 1995, 60, 508.
J. Chem. Soc., Perkin Trans I, 1998, 1769.
Synthesis and Structural Characterization of
BEDT-TTF type - Donors/Acceptors
S
S S
S
S
S
S
S
(CH2)n(CH2)n
n = 4, 5, 6, 12
Major findings
(a) Core C6S8 more planar
(b) Donor properties unchanged
(c) S...S nonbonded interactions decrease
(d) n = 6 onwards, isomers
S
S S
S
S
S
S
S
(CH2)n
(CH2)n
Phane type TTFs isolated
(i) C6S8 core not planar
(ii) Poor donors
1. C6S8 Core planar
2. Stacked uniformly along a axis
3. S S 3.686 Å
BEDT-TTF 3.686 Å (core tub-shaped)
S
S
S
S
S
S
S
S
S
X
S
S
S
S
Ph3P
S S
S
S S
S
S
S
S
S
S
S
S
S
S
SS
S
X
CH3
X = Cl, Br
Functionalised TTFs
Singh et al. Tetrahedron 1997, 11627.
Benzene
Thio-Claisen Rearrangement
Substrates for Intramolecularly Coordinated Organochalcogens
Singh et al.
J. Chem. Soc., Dalton Trans., 1990, 907.
Inorg. Chem., 1992, 32, 1431.
Organometallics, 1995, 14, 4755.
J. Chem. Soc., Dalton Trans., 1996, 2718.
J. Chem. Soc., Dalton Trans., 1996, 1203.
Organometallics, 1996, 15, 1707.
Organometallics, 1997, 16, 563.
Organometallics, 1999, 18, 1986.
Chem. Eur. J., 1999, 5, 1411.
Tetrahedron: Asymmetry, 1999, 10, 237.
Chem. Commun., 2000, 143.
Organometallics, 2003, 22, 5069.
Organometallics, 2004, 23, 4199.
Organometallics, 2006, 25, 382
Chemm. Commun., 2010, 46, 1130
Dalton Trans., 2010, 39, 2010
Dalton Trans., 2011, 40, 4489
Organometallics, 2011, 30, 534
Dalton Trans., 2012, 41, 10714
G
G = NMe2, Cl,OH, SPh
N
Me H
O
N
R1
R2
R1 = H, R2 = HR1 = H, R2 = EtR1 = Me, R2 = Me
O
N
NR*
NHR
O
Fe
CHO
Br
N
O
N
NN
N
O
Se
NO
Se
N
O
Se
Bi
N
O R
R´
SeX
N
O R
R´
BiCl3
n-BuLi
N
O R
R´
ELi
N
O R
R´
E
N
OR
E
N
O R
R´
Li
Hg
N
O
E
N
O
E M
N
O
N
O
E
N
O
Se
N
O
Se Hg
E(dtc)2
R = R´ = Me
R = Et, R ´ = H
E powder
[O]/H2O
R = R´ = Me (E = Se)
E = Se; E = Te
R = R´ = Me R = Et, R ´ = H
R = R´ = Me; E = Se R = Et, R ´ = H; E = Se R = R´ = Me; E = Te
R = R´ = Me; E = Se R = Et, R ´ = H; E = Se R = R´ = Me; E = Te
R´
R = R´ = Me
R = R´ = Me (E = Se)
E = Se; M = Zn E = Se; M = Cd E = Se; M = Hg
E = Te; M = Zn E = Te; M = Cd
R = R´ = Me
Br2 or I2
(E = Se)
R = R´ = Me; X = Cl R = R´ = Me; X = Br R = Et, R ´ = H; X = Br R = R´ = Me; X = I R = Et, R´ = H; X = I
A Typical Sequence of Reactions
Attempted synthesis of [8-(dimethylamino)-1-naphthyl]selenenyl(II) triflate
Se-N 1.862(5)
Se-C(9) 1.887(6)
Se O(2) 2.585(5)
N Se BrAgOTf, 0 oC
MeOH
XN Se OTf
N N
Se
Se
OTf
OTf
1. Coupling of naphthalene rings
2. Demethylation
3. Highly conjugated and blue color
van der Waals radii (Å)
O 1.52
Se 1.90 3.42
300 400 500 600 700 800
0.0
0.2
0.4
0.6
0.8
1.0
1.2
1.4
Ab
so
rba
nce
Wavelength(nm)
pH 5.75
pH 6.06
pH 6.71
pH 7.15
pH 7.64
pH 8.50
pH 9.41
pH 9.93
pH 10.53
300 400 500 600 700 800
0.0
0.1
0.2
0.3
0.4
0.5
0.6
Ab
so
rba
nce
Wavelength(nm)
Compound(20 M)
Compound (20 M)+base(30 M)
Compound (20 M)+base(30 M)+ acid(30 M)
pH titration studies of dication (pH sensor ?)
Possible mechanism
SanjioOrganochalcogens with two coordinating heteroatoms
13
Singh et al.,
Angew. Chem. Int. Edn., 2004, 43, 4513
J. Org. Chem. 2005, 70, 3693.
Significant Torsion Angles (˚) (Ar)
C6-C1-C2-C3 10.1(5)
C2-C3-C4-C5 -7.3(5)
C5-C6-C1-C2 -11.8(5)
All Torsion angles ( ˚ ) (Ar) ~ 0.0
C1-C6-C5-C4 0 .00
C1-C2-C3-C4 0.00
First example of coordinated RSeBr: Observation of aryl ring strainSelvakumar
Singh et al. Chem. Eur. J., 2010, 16, 1057614
Antioxidant enzymes
Catalase is a hemeprotein – Catalyzes the disproportion of H2O2
Superoxide dismutase: Cu-Zn-SOD, Fe-SOD, Mn-SOD– Catalyzes the disproportionation of HO2
Sulfiredoxine is a cysteine containing enzyme - Reduction of H2O2
Glutathione peroxidase is a selenocysteine containing enzyme - Reduction of H2O2
ROOH + 2GSH ROH + GSSG + H2OGPx
In 1973, Flohe & Rotruck discovered the antioxidant enzyme glutathione peroxidase (GPx)
In GPx-catalytic triad involves Sec, Trp and Glnresidues at the active side
Established as the 21st proteinogenic amino acid
Sec-codon UGA
Uniqueness of selenium
Sec least abundant in proteins
In adult human, 140 g S and only mg quantities of Se
Selenium more polarizable, nucleophile, lower redox potential
Flohe, L. Biochim Biophys Acta 2009, 179,1389-1403; Bock, A.; Forchhammer, K.; Heider, J.; Leinfelder, W.; Sawers, G.; Zinoni, F. Mol. Microbiol.
1991, 5, 515-520.
Initial Reduction Rates (ν0) of H2O2 (3.75 mM) with PhSH (1 mM) in methanol in the presence of various selenium catalysts (0.01 mM)
Catalysts ν0 M min-1
0.55 (0.18)
3.39 (0.37)
3.16 (0.52)
3.83 (0.32)
5.78 (0.79)
28.38 (3.88)
Catalysts ν0 M min-1
36.10 (0.12)
574.01 (23.98)
466.49 (28.26)
Inactive Catalysts
[R, S; R, S] (+)
[S, R; S, R] (-)
GPx-Like Activity of Chiral Ferrocenyl Selenium Derivatives
Strong Se N interaction
Does not favor selenol formation
Thiol exchange occurs
Weak Se N interaction
Favors selenol formation
No thiol exchange
Intramolecular Interaction and Thiol Exchange
Mugesh, G.; Singh, H. B. Chem. Soc. Rev. 2000, 29, 347−357.
Mugesh, G.; Panda, A.; Singh, H. P.; Punekar, N. S.; Butcher, R. J. Chem. Commun. 1998, 2227−2228.
Mugesh, G.; Panda, A. Singh, H. B.; Punekar, N. S.; Butcher, R. J. J. Am. Chem. Soc. 2001, 123, 839−850.
ROOH
ROH
H2O
ESe
ESeOH
ESeSG
GSH
GSH
GSSG
H+
O
O
O
O
Li
n-BuLi
Li
O
BrCH2OH
CH2OH
O
O
SeHCl
Se
O
O
O
O
R
R
NH2
MeCNNH2
HH
Se
N
N
R
Se
N
NH
NaBH4
H
EtOHSe
N
N
R
Se
N
N
R
Ether
Se(dtc)2
R = CH2CH2 and
CH2CH2NHCH2CH2
Selenaazamacrocycles
1) Template free synthesis
2) [2+2] condensation without
recourse to high dilution
3) Good yield
4) Hybrid ligands
Se-Se: 3.808 Å
Se-N(1A): 3.010 Å
Se-N(1B): 3.555
C(1A)-Se-C(1B): 98.03(10)
O
O
O
O
Li
n-BuLi
Li
O
BrCH2OH
CH2OH
O
O
SeHCl
Se
O
O
O
O
R
R
NH2
MeCNNH2
HH
Se
N
N
R
Se
N
NH
NaBH4
H
EtOHSe
N
N
R
Se
N
N
R
Ether
Se(dtc)2
R = CH2CH2 and
CH2CH2NHCH2CH2
Selenaazamacrocycles
NHH
HNNH NHNH N
HN
Se
N
Se
HN
Hg
Hg(PF6)2Se
NH
Se
HNH
NH
NH2
H2NNH2
(CF3COO-)6Se
NH2
Se
H2NH2N
(ii) (CF3COO-)2, (excess), MeOH
(i) Hg(CH3COO)2, NH4PF6, MeOH, reflux, 30 min.
(i)
(ii)
Reactions of Selenaazamacrocycles
Hg-Hg1: 2.5358(8)
Hg- N(1B): 2.468(8)
Se….Se: 11.1962
Se….Hg#1: 5.8185
Singh et al.
Chem. Commun., 143, 2000
Chem. Commun., 322-323 (2004)
Inorg. Chem. 43, 8532-8537 (2004)
J. Chem. Soc. Dalton., Trans., 1203,(1996)
NMe2NMe2Fe
O
N
O
N
Single source precursors for Group 12-16 semiconductors
M(ER)2
M E
Zn S
Cd Se
Hg Te
ME (Binary, Ternary
combinations)Metal
Chalcogenolates
Polymeric
Insoluble
Low volatility
Strategies: a) Use of bulky R groups
b) Adduct formation with neutral ligands
R =, ,
O
NE
-Li
+
O
N
O
N[O]
E M E
O
N
E Hg
MCl2
O
N
O
N
Hg
E
MeOH
O
N
O
N
E
EE = S, Se, and Te
E = S and Se
i) n-BuLi ii) E powder
Zinc, Cadmium and Mercury Chalcogenolates
Mass Spectroscopy
Zn(RSe)2+
m/e = 572
Zn2(RSe)3+
m/e = 890
Cd(RSe)2+
m/e = 619
Cd2(RSe)3+
m/e = 985
Hg(RSe)2+
m/e = 709
(no peak corresponding
to dimer)
M(SeR)2
TGA/TDA
Zn(SeR)2
Cd(SeR)2
Zn(SeR)2
ZnSe + R2Se
CdSe + Se
Hg + R2Se2
~300oC
~300oC
~300oC
[RSeR]+
+ MSe
Monomeric,
hydrocarbon soluble,
Crystalline
O
N
E Zn
O
N
E
E = O, S, Se, Te
P21
Chiral space group
1. Enantiomerically pure, interconversion between (P) and (M) helix
slow at room temperature
2. Thiolato- both pure enantiomers and recemic forms isolated
3. Zinc phenolate- -550C AB quartret
4. Zinc tellurolate- -600C AB pattern resolved
Singh et al.
Polyhedran (Report), 1996, 15, 745
J. Chem. Soc., Dalton Trans., 1996, 461.
Inorg. Chem., 1998, 37, 2663.
Eur. J. Inorg. Chem., 1999, 1229.
J. Organomet. Chem., 1999, 577, 293.
Eur. J. Inorg. Chem., 2001, 669.
24
Macrocycles with multiple sites of Lewis acidity
Important features of metallamacrocycles
1. Catalytic activation of electron rich organic and inorganic
substrates
2. Anion transport
3. Selective molecular recognition
4. Sensors
Important features of mercury metallamacrocycles
1. Due to relativistic effects, capable of exhibiting Metal….Metal
interactions between closed shell ions/atoms
2. Linear geometry leads to large cavities
Metallamacrocycles
25
IR 199Hg NMR
1640 cm-1 -690 ppm
1632 cm-1 -683 ppm
1640 cm-1 -683 ppm
IR 1662 cm-1
199Hg NMR -749 ppm
Significant bond distances Å
Hg(1)-C(1A) 2.112(11)
Hg(1)-C(1B) 2.148(12)
Hg(1)-N(1B) 2.65(2)
Hg(1)-N(1A) 2.70(2)
Hg(1)-Hg(2) 4.992(2)
Significant bond angles (° )
C(1A)-Hg(1)-C(1B) 175.2(7)
C(16A)-Hg(2)-C(16B) 175.1(7)
26
Complexation with Cu(I) ion
IR 1627 cm-1
199Hg NMR
-558 ppm
IR 1640 cm-1
199Hg NMR -690 ppm
ΔE value 0.078 V
-538 ppm
27
Cu1-Hg1 2.92, Cu1-Hg2 2.91 Å
Hg1-Hg1# 3.20 Å
Cu1-N1 2.06, Cu1-N2 2.07 Å
Hg1-Cu1-Hg2 177º
Cu1-Hg2-Hg2# 154.4º
Crystal structure of Cu(I) Complex, showing Hg•••Cu,
heterometallic and Hg•••Hg homometallic d10•••d10 interaction
Covalent radii of
Cu = 1.17 Å and Hg = 1.44 Å
Sum of van der Waal’s radii
Hg = 1.75 + Cu = 1.40 = 3.15 Å
For Hg (1.75 + 1.75) = 3.50 Å Singh et al., Angew. Chem. Int. Ed. 2005, 44, 1715.
28
Selected bond lengths (Å)
and angles (º):
Hg-Hg 3.37
Hg∙∙∙N 2.66
Hg-O 2.07 Å
C-Hg-O 178.49
Hg-O-Hg 109.32º
IR 1622 cm-1
199Hg NMR 1044 ppm
Synthesis of Hydroxo-Bridged Mercury Complex
Singh et al., Organometallics 2010, 29, 4265.
30
Hg1-Pd 3.1020(3)
Hg2-Pd 3.2337(3)
Hg1-N1A 2.6662(19)
Hg2-N1B 2.647(2)
Pd-N2A 2.1611(18)
Pd-N2B 2.1602(19)
Hg1-Pd-Hg2 162.898(7)
C1A-Hg-Cl1 165.58(7)
C1B-Hg-Cl2 169.14(7)
Helical structure of Pd complex skeleton
Space filling model
Bond length in (Å) and bond angle in (°)
Singh et al., Angew. Chem. Int. Ed. 2009, 48, 1987.
Sagar
Ph.D. Students
1. Pawan K. Khanna (July 1984-1989)
2. N. Sudha (July 1985 - July 1989).
3. S. Kalyan Kumar (Jan 1986 - Dec. 1991).
4. A. Regini (Jan. 1987 - Jan. 1992).
5. K. Rani (Jan. 1988-1993).
6. Rupinder Kaur (July 1991 to Jan. 1996).
7. Saija C. Menon (July 1991 to July 1996)
8. E.V.K. Suresh Kumar (July 1993 to Feb. 1998)
9. G. Mugesh (July 1994 to July 1998)
10. Arunashree Panda (Jan 1995 to Dec. 99)
11. Sanjio, S. Zade, (Dec. 1999 - 2004)
12. K. Kandasamy, (July 1999 - 2004)
13. Snigdha Panda, (July 1999 - 2004)
14. Sangit Kumar, (July 1999 -2004)
15. Upali Patel, (July 2000-2005)
16. Sagar Sharma (July 2004-2009 Dec)
17. Kriti Srivastava (Jan 2005-2010 Jan )
18. K. Selvakumar (Jan 2005- May 2010)
19. Tapash Chakraborty (Jan 2005-May 2010)
20. Vijay Pal Singh (Jan 2006-May 2011)
21. Sudesh T. Manjare (July 2006-2011)
22. Prakul Rakesh (July 2006-2012)
23. Poonam Shah (July 2007-)
24. Shikha Das (July 2009-)
25. Sangeeta Yadav (July 2010-)
26. Anand Kumar Gupta (July 2010-)
27. Satheeshkumar (July 2011-)
28. Varsha Tuteja (July 2011-)
29. Venkatashwaran (July 2011-)
30. R. Saravanan (July 2012-)
31. S. Aravindhan (July 2012-)
AcknowledgementPost-Doctoral Fellows /Research Assistants
1. Dr. S. Kalyankumar (1991)
2. Dr. Jai Deo Singh (1990-93)
3. Dr. N. Sudha (1994)
4. Dr. Saija C. Menon (1996-97)
5. Dr. G. Mugesh (1998-1999)
6. Dr. Arunashree Panda (Feb.2000-July 2000)
7. Dr. Santosh Kumar Tripathi (July 2001-2004)
8. Sandeep Apte (July 1999-May 2000)
9. Anna Mukharjee (Nov.1999-May 2000)
10. Urmila Patil (July 1999-May 2000)
11. Dr. Rajesh Baligar (August 2005- June 2007)
12. Goutom Mukherjee (May 2007-Dec 2007)
13. Dr. Sagar Sharma (March 2010-Sep 2010)
14. Dr. Kriti Srivastava (Sep 2010- Feb 2011)
15. Dr. K. Selvakumar (April 2010-October 2011)
16. Dr. Sudesh Manjare (October 2011- 2012)
17. Dr. Puspendra Singh (August 10, 2010-)
18. Dr Ninad Ghavale (May 2011-)
19. Dr. Kandasamy Gopal (October 2011-)
Funding Agencies : DST, CSIR, BRNS, DRDO
Prof. R. J. Butcher Prof. R. B. Sunoj
Dr. G. Wolmershauser Prof. N. S. Punekar
Dr. R. P. Patel Prof. S. Durani
Synthesis and Reactivity of First Room Temperature Stable
Organoselenenyl(II) azides
Klapötke and coworkers by employing intramolecular coordination reported the isolation
of first organoselenenyl(II) azide, stable at 0 C.
First room temperature stable organoselenenyl(II) azide by employing intramolecular
coordination and steric hindrance.
[M + Na]+ peak at m/z 575.1342 in HRMS
Klapötke and coworkers, J. Am. Chem. Soc., 2004, 126, 710
N
Se
N3
r.t, 2 h, CuP(OEt)3I
THF: H2O (2:1)Se
N
O
NN
N
N
O
Se
N3
B3LYP/6-31+G(d) level
Kriti
Entry Se−N (Å) E Se…N/O
(Kcal/mol)
1 2.421 23.66
2 2.261 41.58
3 2.342 32.15
4 2.180 54.41
5 2.265 43.16
6 2.377 20.64
N
Se
N3
1 2 3
4 5 6
Singh and coworkers, Dalton Trans., (2010) 39, 10137.
First Structural Characterization of a Selenenyl selenocyanate
(RSeSeCN Unsymmetrical diselenide)
77Se NMR 888, 11513C NMR 15 peak
FT-IR 1599 ( C=N), 2110 ( C≡N)
HRMS [C20H22N2Se2K+ (MK+)
calcd: 488.9750, Found: 488.9773.
N•••Se1 2.116(2)
Se1-Se2 2.6069(4)
Se1-Se2-C20 101.9(2)
C1-Se1-Se2 97.6(8)
van der Waals radii (Å)
N 1.55
Se 1.90 3.45
Prakul
H2N OH
O SOCl2
MeOH H3N O
O
Me
Cl
BrCOCH2Br
Et3N, DCM HN O
O
Me
H2C
Br
O
Na2Se2
NH
OO
Me
CH2
O
Se NH
O O
Me
CH2
O
Se
NHO
O
Me
O
Se
THF,
-72 oC
+
Molecular Structure
77Se = 371 ppm 77Se = 262 ppm
First Structure of Selenocysteine
m.p. = 91 oC
Yield = 40 %
m.p. = 75 oC
Yield = 80 %
77Se = 295 ppm
Stocking et al. J. Chem. Soc., Perkin Trans. 1, 1997, 25, 2443
Te2∙∙∙O7 2.895 Å
Te2∙∙∙O10 2.961 Å Molecular structure
Red Liquid
77Se = 260 ppm
Synthesis of Tellurocysteine derivatives ?
125Te = 814 ppm125Te = 589 ppm
Yield = 70 %
Yield = 80 %
Yield = 40 %
m.p. = 166 oC
m.p. = 177 oC
Glutathione Peroxidase (GPx)
Cytosolic GPx (cGPx) – uses GSH as co-substrate
Reduction of hydrogen peroxides and organic peroxides
ROOH + 2GSH ROH + GSSG + H2OGPx
Tetramer of four identical subunits; each subunit contains a
selenocysteine residue
Catalytic triad – SeCys, Gln, Trp - Selenolate is highly stabilized
Se
N
SeCys H2N
O
Trp148
.....
.....
+HH
Gln70
ROOH
ROH
H2O
ESe
ESeOH
ESeSG
GSH
GSH
GSSG
H+
Epp et al. Eur. J. Biochem. 1983, 133, 51
O
Se
N Ph
O
Se
N Ph
NO2
OH
SeNAc
SeN
O
Ph
O
Se
N Me
N
Me
c-C6H11
Se
N
Se
NMe2
Se
H
Cl-
Se
O
O
)2
)2
)2
+
GPX Mimics
Ebselen
N
Se
O
(1) (2) E = Se; (3) E = Te
2E)
2E)
(4) E = Se; (5) E = Te
2E)
(6) E = Se; (7) E = Te
E)Fe2
(8) E = Se; (9) E = Te
N
E)2
(10) E = Se; (11) E = Te (12) E = Se; (13) E = Te
O
N
E)2
E)
NMe2
2
(18) E = Se; (19) E = Te(14) R = Et, R' = H; E = Se;
(15) R = Et, R' = H; E = Te;
(16) R = R' = H; E = Se
(17) R = R' = H; E = Te
R'R
O
N
E)2
O
PhH
(20) E = Se; (21) E = Te
2E)
N
2E)
(22) E = Se; (23) E = Te
H
NMe2
E)
Me
Fe2
(24) [R,S;S,R] (+); E = Se
(25) [R,S;S,R] (+); E = Te
Singh et al.Chem. Soc. Rev. 2000, 29, 347
Proc. Natl. Acad. Sci. 2000, 70, 207
J. Am. Chem. Soc. 2001, 123, 839-850
Chem. Commun. 2000, 143
Organometallics 2002, 21, 884
Organochalcogen Compounds As a GPx Mimics
Table: Initial reduction rates (v0)[a] of H2O2 (3.75 mM) with PhSH (1 mM)
in the presence of various dichalcogenide catalysts (0.1 mM).
[a]Obtained by Lineweaver-Burk Plots. [b]Standard deviations are shown in parentheses.[C]Inactive at lower concentration.9 [d]Since the reduction rate was too fast to be determined
at 0.1 mM concentration range, 0.01 mM was used for the experiments.9 [e]decomposed
entry catalyst
(E = Se)
v0[b] M.min-1 entry catalyst
(E = Te)
v0[b] M.min-1
a 2 24.08(1.04) b 3 59.52(3.58)
c 4 53.21(5.81) d 5 142.97(5.17)
e 6 31.48(3.07) f 7 70.47(5.40)
g 8 33.92(0.37) h 9 77.61(6.08)
i 10 124.02(7.89) j 11 1629.56(5.67)
k 12c 28.87(1.72) l 13 135.09(10.04)
m 14c 18.53(1.32) n 15 109.38(6.95)
o 16 41.64(1.48) p 17 -e
q 18c 45.34(2.81) r 19 239.00(8.99)
s 20 3.52(0.87) t 21 9.83(1.82)
u 22 inactive v 23 inactive
w 24 574.01 (23.98)d x 25 -e
Organochalcogens with two coordinating heteroatoms
..
Plausible mechanism
Br2
CHO
C
SeO H
HO
CHO
CHO
Se)2
CHO
CHO
SeBr
..
Se
O
O
CHO
OHC
C
Se
OH
Br
8
SeO
CHOOHC Se
O
O
-Br-
H2O
H+-
-
CHO
CHO
Se2
)
CHO
CHO
BrNa2Se2
THF, Reflux, 4h Br2Se
O
O
OHCCHO
SeO
NMe2
Se )2
M min-1
Se OOHC
O
SeOCHO
M min-1
CHO
CHO
Se2
M min-1
)
Space Group: P-1
R value: 0.0349
C7A-O-C7B: 113.12
Se1A…O2A: 2.6042 Å
Se1B…O1B: 2.4647 Å
Se-O bond containing compounds as a GPx mimics
OH OLi
LiTHF
OH
Se
OLi
SeLi
OH
Se
i. n-BuLi
ii. TMEDA Penatne
Se powder
Se(dtc)2
2 2
[O], H2O
Monoclinic
Space group = P2(1)/n
Se(1)-C(11) = 1.934(3) Å
Se(1)-Se(2) = 2.3220(6) Å
C(11)-Se(1)-Se(2) = 101.99(9)o
C(21)-Se(2)-Se(1) = 104.40(9)o
C(12)-C(11)-Se(1) = 116.6(2)o
Orthorhombic
Space group: Pbca
Se-O(1) = 1.794(5) Å
Se-O(2) = 1.630(5) Å
Se-C(1) = 1.939(4) Å
O(2)-Se-O(1) = 105.1(3)o
C(1)-Se=O(2) = 101.4(2)o
C(1)-Se-O(1) = 86.5(3)o
OH
Se Br
OH
Se
O
TBHP
OH
Se
TBHP
SeO
O
OH
SeO
OH
2
i. NaBH4
ii.
[2, 3] shift
-
TBHP
Seleninate Esters:
Se
O
O
OH
Se
H2O2
AcOH2
Monoclinic
Space group: C2/c
Se-O(1) = 1.922(3) Å
O(1a)-H(2) = 2.4476Å
C(2)-H(2)-O(1a) = 111.25()o
O(1)-Se-O(1a) = 174.41(13)
C(1)-Se-C(1a) = 101.74(15)o
C(1)-Se-O(1a) = 92.75(11)o
C(7)-O(1)-Se-O(1a) = -34.68(10)o
C(1)-Se-C(1a)-C(2a) = -97.95(3)o
C(1a)-Se-O(1)-C(7) = -85.22(2)o
Monoclinic
Space Group: P21/c
Se-O1A: 1.9747(14)
O1A-Se-O1B: 172.85(6)
C1A-Se-C1B: 101.42(8)
O
O
Se
[O]
SeO
O
O
O
Se
O
O
Se
O
O
O
OO
O
Monoclinic spacegroup: C2/c
Acta Chem. Scand. 27 (1973) 2219
Monoclinic P21, Optically pure
Chirality 12 (2000) 71
t-Bu
CONHR
E
N
O
R
THFt-Bu
CONHR
CONHR
Br
t-Bu
CONHR
CONHR
SeCH2OCH3
THF
t-Bu
COOH
COOH
Br
t-Bu
CONHR
CONHR
Se
1 2 R = Ph3 R = Me4 R = iPr
5 R = Ph, E = Se6 R = Me, E = Se7 R = iPr, E = Se8 R = Ph, E = S9 R = Me, E = S10 R = Me, E =Te
11 R = Ph12 R = Me13 R = iPr
5, 6, 7
i. SOCl2
ii. RNH2
Li2Se2
i. n-BuLi
ii. (CH3OCH2)2Se2
Li2Se2
)2
Br2
-CH3OCH2Br
-HBr
Synthesis of new Ebselen analogues with intramolecular coordination
Space Group: I2/a
R value: 0.0349
Se1 O2: 2.435 Å
Se1 N1: 1.916 Å
Se1-N1-C7: 115.88
Se1-N1-C8: 119.99
C7-N2-C8: 124.65
51
Theory of closed shell metal-metal (d10-d10) interaction
It is a kind of attractive interaction between closed shell metal ions.
The interaction energy increases down the group i.e.; for heavy metals.
Gold-gold interaction (aurophilicity) is the best example for d10-d10 interaction
The aurophilic bond strength is about 7-12 kcal/mol (comparable
to the strength of a hydrogen bond).
This interaction can be explained by the theory of relativity.
Pyykkö, P; Mendizabal, F. Inorg. Chem. -
Pyykkö, P. Angew. Chem. Int. Ed. , 4412-4456
52
Heavy metals have larger nuclear charge
Heisenberg uncertainty principleVelocity increases (comparable to C);
for gold V1s 0.6C.
Rest mass of the core electrons increases as per equation
mv = m0 /[1-V2/C2]0.5; mv and mo are the moving mass and rest mass
of the electron.
Results in significantly more kinetic energy to the particle
Size of Inner s and p orbitals shrinks
To maintain orthogonality, the s- and p-orbitals of higher quantum
number also contract and shield the nucleus more
d and f orbital expand radially and increase in energy
d and f orbital are therefore more destabilized and
polarisable
Relativistic effect
Core electrons are subjected to greater electrostatic field hence Volume
decreases.
53
Synthesis of (o-formylphenyl)mercury, precursor for the
synthesis of mercuraaza macrocycle
IR 3122 cm-1 1662 cm-1
199Hg NMR -689 ppm -749 ppm
Upali
E
O
N
E = S/Se
E
O
N
Cd
TOPO/TOP2700C
CdS/CdSe + R2S/R2Se
Hexagonal CdS
Particle size calculated Powder X-ray Diffraction Pattern of CdS
from Scherrer’s Equation
For CdS = ~5-7 nm
Hexagonal CdSe
Particle size calculated Powder X-ray and Electron Diffraction
from Scherrer’s Equation Pattern of CdSe
For CdSe = ~10-12 nm
SEM photograph of CdSe
Particle size 4-5 microns
Preparation of CdS and CdSe nanoparticles
TEM micrograph of CdSe
Particle size 200-250 nm
Te Hg
O
N
TeLi Te
O
N
O
N
O
N
E Hg
ELi
2
2
i) n-BuLi, Et2O, Te0, 0
oC, 2 h ii) [O]/H2O iii) Hg, MeOH, rt, 24 h.
(i) (ii)
(iii)
(i) (ii)
(iii)
(1) (2) (3)
(4)
(5) (6) (7)
(8)
2
O
N
O
N
O
N
O
N
E2
E = Se/Te
Synthesis of mercury chalcogenolates