Structural and Electronic Properties of Phosphino(oligothiophene) Gold(I) Complexes

A series of gold(I) complexes containing phosphino(oligothiophene) ligands of varying conjugation length has been
prepared. Solid state crystal structures of (PT3)AuCl (PT3 = 5-diphenylphosphino-2,2‘:5‘,2‘ ‘-terthiophene) and AuCl(PTP)AuCl (PTP = 2,5-diphenylphosphinothiophene) have been obtained. The complex AuCl(PTP)AuCl crystallizes
as a dimer with two intermolecular Au−Au contacts. Variable temperature NMR spectroscopy is used to demonstrate
the presence of aurophilic interactions in solution for AuI(PTP)AuI. Dual emission is observed for AuCl(PTP)AuCl
in solution and is attributed to emission from both monomer and dimer. In the solid state, dimer emission is dominant.
The iodo analogue, AuI(PTP)AuI, shows only low energy dimer emission in both solution and the solid state.
Compounds in which the ligands contain longer bridges (either bithienyl or terthienyl) show absorption and emission
bands due to the π−π* transition only, both in solution and the solid state.