Platinum and rhodium complexes of dialkenyl telluroether ligands: synthesis, dynamic nuclear magnetic resonance and crystal structure of cis-dibromo(3,3,7,7-tetramethyl-5-tellura-3,7-disilanona-1,8-diene)platinum(II)

Abstract

A number of dialkenyl telluroether ligands have been synthesised. Reaction with platinum(II) and rhodium(I) metal centres at low temperature in non-aqueous media yielded complexes in which the ligands are bidentate (binding through the tellurium atom and one alkene function) and tridentate, respectively. The bidentate platinum complexes are fluxional, exhibiting exchange of the alkene moieties, the energy barriers for which have been evaluated. Tellurium-125 NMR data have been obtained and are discussed with reference to the chelate ring effect. The crystal structure of [PtBr₂{Te(CH₂SiMe₂-CHCH₂)₂}] has been determined: crystals are triclinic of space group P with a= 6.5837(9), b= 8.8594(8), c= 17.860(2)Å, α= 98.65(2), β= 97.73(1), γ= 111.26(1)° and Z= 2. The structure is monomeric with the platinum atom exhibiting square-planar geometry. The two bromine atoms are mutually cis and the di(silaalkenyl) telluroether ligand chelates to the metal via the tellurium atom and one alkene moiety.