Exchange at Platinum II by Dissociative Processes

The complexes ci5-[PtPh2L2] (L are thioethers) lose L in solution according to Eq. (9). Replacement kinetics for the substitution of L by bipy in CH2CI2 follows rate law (10), identical to those found for related reactions for which dissociative 

2cis-[PtPh2L2] [Pt2Ph4(/i-L)2] + 2L kobs = a[hipy]/(b[L] + [bipy]) + c[bipy] 

Despite steadily accumulating evidence over the years that some reactions of some platinum complexes proceed by ligand dissociation to three-coordinate T-shaped 14-electron intermediates, and notwithstanding the persuasive activation volume data reported above, the inability of kinetic data alone to rule out the intervention of solvent intermediates as alternative pathways has always left room for doubt. Thus a paper on the reversible loss of olefin from tran5-[PtCl2(ol)L] 

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