NUCLEAR-MAGNETIC-RESONANCE INVESTIGATION OF THE HYDROGEN-PEROXIDE OXIDATION OF PLATINUM(II) COMPLEXES - CRYSTAL AND MOLECULAR-STRUCTURES OF SODIUM TRANS-DIHYDROXOBIS(MALONATO)PLATINATE(IV) HEXAHYDRATE AND SODIUM TRANS-DIHYDROXOBIS(OXALATO)PLATINATE(IV) HEXAHYDRATE

Nuclear magnetic resonance techniques utilizing Pt-195 and C-13 have been employed to study the formation of dihydroxo platinum(IV) compounds in the hydrogen peroxide oxidation of Pt(II) complexes. The trans-dihydroxo isomer is the exclusive kinetic product for oxalato, malonato, and chloro complexes. Isotopic labeling experiments with (H2O)-O-18 demonstrate that one hydroxo ligand originates from hydrogen peroxide, while the trans hydroxo ligand originates from water. Hydrogen peroxide oxidation in methanol or ethanol results in the formation of transhydroxomethoxo- and trans-hydroxoethoxoplatinum(IV) complexes, respectively. The structure of sodium trans-dihydroxobis(malonato)platinate(IV) hexahydrate has been determined by X-ray crystallography: P1BAR, a = 6.648(l) angstrom, b = 8.234(l) angstrom, c = 9.065(1) angstrom, alpha = 63.82(1)-degrees, beta = 70.67(l)-degrees, gamma = 71.78(1)-degrees, V = 412.0(1) angstrom3, Z = 1, R = 0.0308, R(w) = 0.0300. The structure of sodium trans-dihydroxobis(oxalato)platinate(IV) hexahydrate has also been determined by X-ray crystallography: Cmca, a = 15.562(2) angstrom, b = 7.200(1) angstrom, c = 13.840(1) angstrom, alpha = beta = gamma = 90-degrees, V = 1550.9(3) angstrom3, Z = 4, R = 0.0509, R(w) = 0.0492.