Thiocarboxylate complexes

In a review of the stereochemistry of a-hydroxycarboxylate complexes, Tapscott includes the structural chemistry of complexes that contain ligands in which a sulfur atom is attached to a carbon a to a carboxylic group. This includes both a-mercapto and a-thioether groups. Lists of structural bonding parameters for a-thiocarboxylate complexes are given together with parameters for chelate rings. 

The complexes were shown to be monomeric in the solid state and have monodentate S-thiocarboxylate ligands. The thiocarboxylic anhydride elimination was studied by 1H and 13C NMR in solution, varying the R group and solvent.858... 

In the absence of electron-withdrawing ligands, disilanes possess only a little Lewis acidity consequently, they show a limited propensity to form hypervalent complexes. Starting from the symmetric methylchlorodisilanes ClMe2SiSiMe2Cl and Cl2MeSiSiMeCl2 as well as carboxylic acids and thiocarboxylic acids, Kawashima et al. have prepared rare examples of penta- and hexacoordinated disilene, namely compounds 886-889 (Scheme 125).855 856... 

Following the formation of the acyl adenylate the reactions will proceed along different paths. In the MoaD-MoeB complex a thiocarboxylate will be formed and the current knowledge regarding this step has been summarized (Section 3.3.5.). 

Red or blue, variously hydrated chromium(II) complexes of thiocarboxylic acids, e.g. S[(CH2)2SCH2C02H]2, have been isolated, and the red complexes are antiferromagnetic.205 Some antiferromagnetic complexes of adenine may have binuclear structures (Table 16). 

Nickel(II) complexes with either bidentate mononegative ligands, such as dithiocarbamates, phosphorodithioates and thiocarboxylates, or monodentate neutral and anionic ligands are generally square planar. Nickel(II) complexes with Se and Te donors are strictly similar to those with S donors. 

There is some work on dithioformato complexes, but clearly thiocarboxylate osmium chemistry is an area in need of further study. 

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