DIMETHYLPLATINUM COMPLEXES OF POLYDENTATE ALKENE-SULFUR AND ALKENE-SELENIUM LIGANDS

Interaction of [PtMe2(SMe2)2] with 1 equivalent of 5-selenanona-1,8-diene produces a monomeric complex containing the ligand chelating through one alkene moiety and the selenium atom. The uncoordinated alkene moiety undergoes exchange with the co-ordinated alkene moiety which has been studied by dynamic NMR spectroscopy. Interaction of the same platinum(II) precursor with 0.5 mol equivalent of the dialkenyl chalcogenoether ligands E(CH2CH2CH = CH2)2 (E = S or Se) produced the novel dinuclear complexes [Pt2Me4{mu-E(CH2CH2CH = CH2)2}] both of which have been characterised by X-ray crystallography and shown to be isostructural. The unit cells are of dimensions a = 1 0.850(2), b = 11.289(7) and c = 1 2.41 5(l) (E = S) and a = 11.056(1), b = 11.251 (1) and c = 1 2.546(2) angstrom, (E = Se). In each case the two metals are bridged by a tetrahedrally co-ordinated chalcogen atom, with one alkenyl group chelating to each platinum atom. The platinum-chalcogen distances are Pt-S 2.354(8) and Pt-Se 2.457(5) angstrom.