Synthesis and β-hydrogen elimination of water-soluble dialkylplatinum(II) complexes in water

Water-soluble cis-dialkylplatinum(II) complexes cis-[PtR2L2] (L-2 = 2 TPPTS, 2 THMP, DHMPE; R = Me, Et, Ph) have been prepared by ligand displacement reactions of [PtR2(1,5-COD)] with L-2. They are stable in water; the diethyl-platinum(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 degreesC. 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.