Mechanism of Ketone and Alcohol Formations from Alkenes and Alkynes on the Head-to-head 2-Pyridonato-Bridged cis-Diammineplatinum(III) Dinuclear Complex

Reactions of the head-to-head 2-pyridonato-bridged cis-diammineplatinum(III) dinuclear complex having nonequivalent two platinum atoms, Pt(N2O2) and Pt(N4), with p-styrenesulfonate, 2-methyl-2-propene-1-sulfonate, 4-penten-1-ol, and 4-pentyn-1-ol were studied kinetically. Under the pseudo first-order reaction conditions that the concentration of the PtIII dinuclear complex is much smaller than that of olefin, a consecutive basically four-step reaction was observed:  the olefin π-coordinates preferentially to the Pt(N2O2) in the first step (step 1), followed by the second π-coordination of another olefin molecule to the Pt(N4) (step 2). In the next step (step 3), the nucleophilic attack of water to the coordinated olefin triggers the π−σ bond conversion on the Pt(N2O2), and the second π-bonding olefin molecule on the Pt(N4) is released. Finally, reductive elimination occurs to the alkyl group on the Pt(N2O2) to produce the alkyl compound (step 4). The first water substitution with olefin (step 1) occurs to...