2 , DPPBTS), to establish the stability of the platinum methyl bond in aqueous solution. From pH ) 3 to 14 there is no reaction other than ligand substitution of H 2 O or OHfor Cl -; there is no CH 3 OH elimination. At lower pH's protonolysis of the Pt-Me bond occurs, producing CH 4 . Dissolving PtMe 2 L 2 into a solution of HCl at pH ) 1 rapidly produces PtCl 2 L 2 for the bidentate ligands, but trans-Pt(Cl)(Me)L 2 is observed for the monodentate ligands. trans-PtClMe(TPPTS) 2 undergoes protonolysis very slowly, indicating an important role for geometry in protonolysis reactions. The protonolysis reactions occur stereospecifically but are sometimes accompanied by cistrans isomerization. The cis or trans thermodynamic preferences, cis-PtCl 2 L 2 , cis-PtMe 2 L 2 , cis-Pt(OH)(Me)L 2 , trans-Pt(Cl)(Me)L 2 , and trans-Pt(H 2 O)(Me)L 2 + , are not easily explained.Platinum and palladium complexes are catalysts for many reactions. [1][2][3][4] In a number of cases, the product formation involves β-hydride elimination; relatively few involve reductive elimination. A number of reactions such as hydrogenation, hydration, hydroamination, and methane to methanol could involve reductive elimination. Goldberg has shown that reductive elimination can occur from Pt(IV) complexes, with formation of carboncarbon or carbon-oxygen bonds. 5 Protonolysis reactions of Pt(II) alkyl complexes in CH 3 OH have been the subject of a few studies. Reactions of trans-Pt(Me)(X)-(PEt 3 ) 2 with triflic acid produced methane, possibly through a Pt(IV) hydride. Deuterium labeling showed extensive incorporation into the CH 4 . 6 A study of HBF 4 or HCl reaction with cis-PtR 2 (PEt 3 ) 2 in CH 3 OH showed cleavage of one Pt-R (R ) Me, Et, etc.) and a slow cis to trans isomerization. 7 In this protonolysis a 10 4 increase was shown for C 2 H 6 elimination over CH 4 . 7 Protonolysis studies on platinum(II) alkyls and aryls showed that acid strength was very important, halide sometimes had an effect, steric hindrance occurred, and aryl cleavage was slower than alkyl, but could not distinguish the site of protonolysis. 8 Florinated bidentate phosphines examined by Roddick and co-workers were much less prone to methyl protonolysis. 9 The dimethyl complexes required neat acids and the monomethyl complexes required neat acids at elevated temperatures. 9 The recent interest in water-soluble organometallic complexes as potential "green" approaches to catalysis raises questions regarding the stability of metal alkyl bonds in aqueous solutions. In this article, we use cis-PtMe 2 (TPPTS) 2 , trans-Pt(Cl)(Me)(TPPTS) 2 , PtMe 2 (LL), and Pt(Cl)(Me)(LL) (TPPTS ) P(m-C 6 H 4 SO 3 Na) 3 , LL ) (m-C 6 H 4 SO 3 Na) 2 PCH 2 CH 2 P(m-C 6 H 4 SO 3 Na) 2 , DPPETS; (m-C 6 H 4 SO 3 Na) 2 PCH 2 CH 2 CH 2 P(m-C 6 H 4 SO 3 Na) 2 , DP-PPTS; (m-C 6 H 4 SO 3 Na)PCH 2 CH 2 CH 2 CH 2 P(m-C 6 H 4 SO 3 -Na) 2 , DPPBTS) (throughout this article LL is generic for one of the three bidentate ligands and L 2 is generic for two TPPTS ligands or one of the bidentate ligands) to examin...