Rearrangements involving changes in metal-ligand binding sites

1 Rearrangements involving changes in metal-ligand binding sites 

Linkage isomerism has been the subject of several reviews. - Much recent work has dealt with nitro-nitrite isomerizationlO and thiocyanate-isothiocyanate isomerization.11 12 Examples of linkage isomerism involving cyanate, methanesulfinate, terpyridyl, alizarin, dihydroxybenzoate, and acetone complexes have been reported also. Some additional examples are discussed in paragraphs that follow. Thus, the rate of M-CN/M-NC linkage isomerization at chromium has been studied, Eq. 11.1. 

The fulminate complex, [Et4N][W(CNO)(CO)5], isomerizes to give an isocyanate complex, [Et4N][W(NCO)(CO)5l, in a variety of solvents.23 The solvent-dependent rate of isomerization was found to increase in the order tetrahydrofuran acetone chloroform dichloromethane. Isomerization did not take place in methanol due to stabilization of the fulminate by hydrogen bonding with the solvent. 

The equilibrium was found to lie almost entirely to the right. Increasing the acidity of the medium led to an increase in the rate of isomerization which also was found to occur in the solid state, but at a significantly reduced rate. 

Other examples of linkage isomerization of dialkyl sulfoxide complexes have been reported by Taube and coworkers.3233 

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