Thiolate bridges

Another method for reductive dimerization has been developed in hy-drosilylation. NiCl2-SEt2 is an effective catalyst in silylative dimerization of aromatic aldehydes with a hydrosilane (Scheme 12) [40]. A catalytic thiolate-bridged diruthenium complex [Cp RuCl(/ 2-SPrI)2RuCp ][OTf] also induces the conversion to 1,2-diaryl-1,2-disiloxyethane [41]. A dinuclear (siloxyben-zyl)ruthenium complex is considered to be formed, and the homolytic Ru - C bond fission leads to the siloxybenzyl radicals, which couple to the coupling product 14. 

The reaction of thiolate ligands with [Ni(terpy)Cl2] in MeOH or MeCN affords different products depending on the basicity and bulk of the thiolate ligand employed. Thus, the reaction with PhSH yields the thiolate bridged dimer [Ni(terpy)(SPh)2]2-6CH3OH (281), reaction with C6F5SH yields the... 

Thiolate-bridged dinickel complexes and, in particular, heterobimetallic Ni/Fe complexes have attracted much interest as model systems for the hydrogenase enzymes. A review covering this... 

A pinacol-type silylative dimerization of various aromatic aldehydes promoted by a cationic thiolate-bridged diruthenium complex has been reported by Flidai and co-workers (Equation (28)).344 l,2-Diaryl-l,2-disiloxyethanes 153 were isolated as the major products along with the corresponding arylmethyl silyl ethers as minor products. 

The stoichiometric reaction of (PhS)2 with Cp RuCl(cod) gives a thiolate-bridged diruthenium complex, which also shows a high catalytic activity for the addition to alkenes (Equation (73)). 

Davies, S. C., Evans, D. J., Hughes, D. L., Longhurst, S. and Sanders, J. R. (1999) Synthesis and structure of a thiolate-bridged nickel-iron complex Towards a mimic of the active site of NiFe-hydrogenase. Chem. Commun., 1999, 1935-6. 

Lai, C.-H., Reibenspies, J. H. and Darensbourg, M. Y. (1996) Thiolate bridged nickel-iron complexes containing both iron(O) and iron(II) carbonyls. Angew. Chem. Int. Ed. Engl., 35, 2390-3. 

Muller, A. and Henkel, G. (1996) [Ni5S(Sbuf)5] and [Ni3S(Sbut)3(CN)3] , novel complexes with sulfur-capped, thiolate-bridged polygonal metal frames. Chem. Commun., 1996,1005-6. 

Osterloh, F., Saak, W, Haase, D. and Pohl, S. (1997) Synthesis, X-ray structure and electrochemical characterization of a binuclear thiolate bridged Ni-Fe-nitrosyl complex, related to the active site of NiFe hydrogenase. Chem. Commun. (Cambridge), 1997, 979-80. 

Steinfeld, G. and Kersting, B. (2000) Characterisation of a triply thiolate-bridged Ni-Fe amine-thiolate complex Insights into the electronic structure of the active site of [NiFe] hydrogenase. Chem. Commun., 2000, 205-6. 

A series of studies deals with the catalytic activity of the dinuclear thiolate-bridged rhodium complex [ Rh( i-S Bu)(CO)(TPPTS) 2] in the hydroformylation ofpropene, 1-hexene and 1-octene (Scheme 4.4) [76-80]. Turnover frequencies up to 3100 h" were detected. 

Scheme 7.4 The first thiolate-bridged diruthenium complexes.

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