Platinum metal complexes of potentially chelating alkene thioether and selenoether ligands: the synthesis and dynamic nuclear magnetic resonance study of [MX2{E[(CH2)nCRCR2]2}](M = Pt or Pd; X = Cl, Br, or I; E = S or Se; n= 2 or 3; R = H or Me) and the X-ray crystal structure of cis-di-iodo-(5-thianona-1,8-diene)platinum(II), [PtI2{S[(CH2)2CHCH2]2}]

Abstract

A variety of potentially tridentate dialkenyl chalcogenide ligands have been found to act as bidentate ligands in platinum(II) halide complexes. The complexes undergo a very facile fluxional process whereby the pendant, unto-ordinated alkene moiety displaces the co-ordinated alkene moiety. Inversion of configuration at the pyramidal chalcogen atom is also observed and the energy barrier for this is typical of dihalogeno-platinum(II) chalcogenide complexes and much greater than the energy barrier for the alkene-replacement process. The molecular structure of a representative species, [PtI₂{S[(CH₂)₂CHCH₂]₂}], has been determined. The crystals are monoclinic with space group P2₁/n with Z= 4 in a unit cell of dimensions a= 13.249(3), b= 8.804(3), c= 11.656(3)Å, and β= 101.05(2)°. The pendant chain is positioned at maximum displacement from the co-ordination sphere of the metal.