Associative Ligand Exchange at Square-Planar Palladium II

Dynamic NMR spectroscopic methods have been used to study more inversions of coordinated sulfur. The rate of S-inversion of compound (2) varies little with the nature of the solvent, in keeping with a process involving no Pt—S bond breaking. Two separate sulfide inversions were detected in compound (3). The 

Associative Ligand Exchange at Square-Planar Palladium(II) 

Above pH 9, the concentration of the aquo ion is very small and the reaction consequently very slow, but significant deviations in the kinetics are observed, resulting in a positive intercept. This enhanced lability is suggestive of conjugate base formation by deprotonation of dien, but since it is also observed in the 

Mes-dien and Ets-dien complexes this explanation cannot hold. The explanation presented is that, under these conditions, the reverse aquation of the product [PdI(R5-dien)] becomes important, significantly boosting the small concentrations of the aquo ion available for the anation reaction. 

The natures of palladium aquo cations in solution have again come under scrutiny. A study of [Pd(OH2)2(biL)] (biL is bipy or phen) lead to the conclusion that it is virtually nonexistent in aqueous solution at normal Its acidic 

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