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Cobalt-mediated direct and selective aromatic thiolation in the complex [Co-III(o-SC6H4N=NC5H4N)(2)]ClO4. Synthesis, spectroscopic characterisation and electron-transfer properties

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Title Cobalt-mediated direct and selective aromatic thiolation in the complex [Co-III(o-SC6H4N=NC5H4N)(2)]ClO4. Synthesis, spectroscopic characterisation and electron-transfer properties
 
Creator SANTRA, BK
LAHIRI, GK
 
Subject alkyl-halides
chemistry
ruthenium(ii)
reduction
family
bond
hydrodesulfurization
alkenyl
spectra
metals
 
Description The reaction of K[SC(S)OR] (R = Me, Et, Pr-n, Pr-i, Bu-n, Bu-i or CH2Ph) with the complex [(CoL3)-L-II][ClO4](2) . H2O 1 [L = phenyl(2-pyridyl)diazene, C6H5N=NC5H4N] in boiling dimethylformamide resulted in [(CoL)-L-III'(2)]ClO4 2 (L' = o-SC6H4N=NC5H4N). In complex 2 the o-carbon-hydrogen bond of the pendant phenyl ring of both the parent ligands L has been selectively and directly thiolated via carbon-sulfur bond cleavage of the dithiocarbonate. During the thiolation the metal ion is oxidised from the starting Co-II in 1 to Co-III in the final product 2. The reaction is highly sensitive to the nature of the solvent used, taking place only in those having high boiling points and relative permittivities. Its rate is dependent,n the: nature of the R group present in the thiolating agent, following the order Me approximate to Et > Pr-n > Bu-n > Pr-i > Bu-i much greater than benzyl. A meridional configuration (cis-trans-cis with respect to the sulfur, azo and pyridine nitrogens respectively) has been established by H-1 and C-13 NMR spectroscopy. The complex exhibits reversible Co-III reversible arrow Co-II reduction at -0.135 V and four ligand-based azo (N=N) reductions at -0.51 (one electron) and at -1.175 V (simultaneous three-electron reduction) respectively versus saturated calomel electrode. The oxidation of the co-ordinated thiol group occurs at 0.90 V.
 
Publisher ROYAL SOC CHEMISTRY
 
Date 2011-08-28T08:24:36Z
2011-12-26T12:57:57Z
2011-12-27T05:46:30Z
2011-08-28T08:24:36Z
2011-12-26T12:57:57Z
2011-12-27T05:46:30Z
1997
 
Type Article
 
Identifier JOURNAL OF THE CHEMICAL SOCIETY-DALTON TRANSACTIONS, (11), 1883-1888
0300-9246
http://dx.doi.org/10.1039/a700018i
http://dspace.library.iitb.ac.in/xmlui/handle/10054/11692
http://hdl.handle.net/10054/11692
 
Language en