Late-metal-thiolate bond

This greater strength of the late-metal-thiolate bond compared to the early-inetal-thi-olate bond or the late-metal-alkoxide bond has been rationalized in two ways. First, the late-metal-thiolate bond involves the favorable match of a soft ligand with a soft metal. Second, this bond involves a larger covalent component than the bond of a late metal to an alkoxide or an early metal to a thiolate. ... 

The pKa value reflects the formation and dissociation constants of metal-carboxylate bonds. The dissociation is prevented by the presence of NH 0 hydrogen bonds of coordinating carboxylate because the NH O hydrogen bonds lower the pKa value of the corresponding carboxyUc acid [65-67]. The hydrogen bonds toward the coordinating oxygen or sulfur atom of pheno-late [63] or thiolate have a similar fimction with each other [43,68). 

There is a further complication. Some metals, especially the late transition and post-transition metals, engage long bonds—secondary coordination—in addition to the regular primary bonds. This is prevalent in mercury thiolate... 

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