Ion-molecule reactions of "rollover" cyclometalated [Pt(bipy-H)](+) (bipy=2,2'-bipyridine) with dimethyl ether in comparison with dimethyl sulfide: an experimental/computational study.

The ion-molecule reactions of dimethyl ether with cyclometalated Pt(bipy-H) were investigated in gas-phase experiments, complemented by DFT methods, and compared with the previously reported ion-molecule reactions with its sulfur analogue. The initial step corresponds in both cases to a platinum-mediated transfer of a hydrogen atom from the ether to the (bipy-H) ligand, and three-membered oxygen- and sulfur-containing metallacycles serve as key intermediates. Oxidative C--C bond coupling ("dehydrosulfurization"), which dominates the gas-phase ion chemistry of the Pt(bipy-H) ion with dimethyl sulfide, is practically absent for dimethyl ether. The competition in the formation of C(2)H(4) and CH(2)X (X=O, S) in the reactions of Pt(bipy-H) with (CH(3))(2)X (X=O, S) as well as the extensive H/D exchange observed in the Pt(bipy-H)/(CH(3))(2)O system are explained in terms of the corresponding potential-energy surfaces.