Platinum(II)-mediated dehydrosulfurization and oxidative carbon-carbon coupling in the gas-phase decomposition of thioethers

The ion/molecule reaction (IMR) of "roll-over" cyclometalated [Pt(bipy-H)]+ (1) (bipy = 2,2'-bipyridine) with dimethyl sulfide (2) leads to the loss of ethene in the main reaction channel (55%); this corresponds to a formal dehydrosulfurization accompanied by the dehydrogenative ("oxidative") C-C coupling of the two methyl groups in dimethyl sulfide to form ethene. In order to obtain deeper insight into this rare reaction, the IMRs of 1 with several symmetric, asymmetric as well as cyclic thioethers and some thiols are probed. Common to many substrates is the formal transfer of H2S from the organic sulfur compound to the [Pt(bipy-H)]+ core accompanied by the expulsion of one or more alkene units. In contrast to the behavior of [Pt(bipy-H)]+ (1), bare Pt+, diatomic PtH+, and also the complex [Pt(phpy-H)]+ (phpy = 2-phenyl pyridine) are not able to bring about dehydrosulfurization. It is accordingly suggested that the (bipy-H)-ligand does not only affect the electronic structure of the platinum(II) core but, moreover, plays an active role as an acceptor in the initial hydrogen transfer from the thioether ligand to the LPt+ core (L = heterocyclic ligand).