Luminescent platinum complexes containing phosphorus-linked silole ligands

Abstract

A series of Pt(II) complexes containing silole-based ligands with diphenylphosphino groups terminally bound to a conjugated organic linker unit coordinated to the silole ring in the 2- or 2,5-positions, 1,1-dimethyl-2-(5′-diphenylphosphino-2′-thienyl)-3,4-diphenylsilole (4), 1,1-dimethyl-2,5-bis(5′-diphenylphosphino-2′-thienyl)-3,4-diphenylsilole (5), and 1,1-dimethyl-2,5-bis(4′-diphenylphosphinophenyl)-3,4-diphenylsilole (8), have been prepared from (cod)PtX₂ (X = Cl, Me, C₂Ph) precursors. Mononuclear, cis-P₂PtX₂ (P = 4) complexes 6–7 were produced from silole 4 whereas dinuclear macrocyclic, cis-cis-X₂Pt(P–P)₂PtX₂ (P–P = 5 or 8) complexes 9–13 were produced from siloles 5 and 8. The solid state structure of the dinuclear complex 13 obtained from reaction of (cod)Pt(C₂Ph)₂ with silole 8, was confirmed by X-ray crystallography. The optical properties of the siloles and the platinum complexes were studied by UV-vis and fluorescence spectroscopy in solution and were found to exhibit long wavelength absorption and emission bands attributed to the π–π* transitions of the silole core.