Pt(M viM vi) x (M viM vi = 1.3-divinyltetramethyl disiloxane), 1, was reacted with dimethyl fumarate to give 2. Compound 2 was investigated by 1H and 13C NMR spectroscopy which showed it to be a mono-nuclear platinum compound containing one dimethyl fumarate and one chelating M viM vi ligand. The reaction of 1 with dimethyl maleate gave 3 which was analogous in structure to the fumarate product as shown by 1H and 13C NMR spectroscopy and extended X-ray absorption fine structure spectroscopy (EXAFS). The EXAFS analysis showed the presence of Pt-C bonds and a through space close contact between Pt and the O from the carbonyl. The NMR assignments were confirmed by comparing the NMR spectra of 2 and 3 with that of (PPh 3)Pt(M viM vi), 4. Reaction of 2 or 3 with an excess of an SiH-containing compound (either MD HD HM (MD HD HM = 1,3-bis(trimethylsiloxy)-1,3-dimethylsiloxane) or Et 3SiH) gave 5 in all cases. Compound 5 contains an alkyl succinate ligand. Hydrogenation of the fumarate ligand (of 2) or of the maleate ligand (of 3) occurs by reaction with SiH; 5 appears to be an intermediate in the hydrogenation process. The reaction between 4, dimethylmaleate, and MD HD HM also gives dimethyl succinate. Differential scanning calorimetry was used to compare the effectiveness of the inhibitors in a curable formulation composed of vinyl-stopped-polydimethyl siloxane, polydimethylsiloxanemethylhydrogen-copolymer, a platinum catalyst and either a maleate or fumarate inhibitor.