Synthesis and (beta)-Hydrogen Elimination of Water-Soluble Dialkylplatinum(II) Complexes in Water

Water-soluble cis-dialkylplatinum(II) complexes cis-[PtR2L2] (L2 = 2 TPPTS, 2 THMP, DHMPE; R = Me, Et, Ph) have been prepared by ligand displacement reactions of [PtR2(1,5-COD)] with L2. They are stable in water; the diethylplatinum(II) complexes cis-[PtEt2(TPPTS)2] undergo preferential disproportionation of the ethyl groups in water, giving ethylene and ethane in 1 : 1 ratio via (beta)-hydrogen elimination in preference to protonolysis at 80 °C. A retardation effect of added free TPPTS on the reaction rate and a deuterium labelling study suggest a mechanism involving prior dissociation of TPPTS for reversible (beta)-hydrogen elimination.