Formation mechanism of head-to-head amidato-bridged acetonylplatinum(III) binuclear complexes - Kinetic evidence for π-coordination of the enol form of a ketone in a ligand substitution reaction

Reactions of head-to-head (HH) α-pyridonato- and pivalamidato-bridged platinum(III) binuclear complexes withacetone were investigated kinetically. The reactions with acetone proceeded slowly to form acetonyl PtIII binuclear complexes in two steps. A mechanism, which involves π-coordination of the enol form of acetone in the first step, followed by the π–σ bond conversion in the second step, is proposed. π-Coordination of the enol was strongly supported by kinetic analyses of a ligand substitution reaction involving the pivalamidato-bridged PtIII binuclear complex with (4-hydroxyphenyl)pyruvic acid. Only the enol form was reactive towards the PtIII dimer complex.