Thiolates, multiple bonding

Hydrosulfido complexes, which contain M-SH groups, can react by an additional pathway unavailable to metal-thiolate complexes. Hydrosulfido complexes can react by cleavage of the S-H group to generate metal-sulfido complexes. The synthesis and reactivity of sulfido complexes are described in Qrapter 13 (metal-ligand multiple bonds). 

A few final comments should be made on the insertions of substrates containing C-C multiple bonds into the bonds between a transition metal and an electronegative heteroatom. First, insertions of olefins into related thiolate and phosphide complexes are as rare as insertions into alkoxo and amido complexes. Reactions of acrylonitrile into the metal-phosphorus bonds of palladium- and platinum-phosphido complexes to give products from formal insertions have been observed, and one example is showm in Equation 9.90. However, these reactions are more likely to occur by direct attack of the phosphorus on the electrophilic carbon of acrylonitrile than by migratory insertion. Second, the insertions of alkynes into metal-oxygen or metal-nitrogen covalent bonds are rare, even though the C-C ir-bond in an alkyne is weaker than the ir-bond in an alkene. 

Fig. 12 FeS4 cluster of oxidized C. pasteurianum rubredoxin (PDBID 1IR0). The OSC consists of multiple hydrogen-bonds donated from backbone amides directly to cysteine thiolates...

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