Kinetics and mechanism of the reactions of platinum(II)-dipicolinate and platinum(II)-glycyglycine with oxalate ion

摘要

The kinetics of the reactions of [Pt(dipic)(H_2O)] and [Pt(digly)(H_2O)] (where H_2dipic = pyridine-2,6-dicarboxylic acid and H_2digly = glycylglycine) with oxalate ion were studied at 25 deg C in aqueous medium by UV-vis spectroscopy at I = 0.1 mol dm~(-3) over an wide range of pH. A probable associative pathway may involve a five-coordinate intermediate leading to the formation of an unidentate oxalate species, which converts to bidentate chelate in subsequent fast steps. The products are isolated and characterized by CHN analysis. IR, and ~1H NMR spectra. The kinetic data from pH variation experiments are fitted by a computer program to a sequence of reactions of the different rate constants are evaluated.