Synthesis and characterization of gold(I) complexes with a triphosphine ligand having a bent trinuclear core interacted with a halide anion

The reaction of [AuCl(PPh3)] with bis(diphenylphosphinomethyl)phenylphosphi ne (dpmp) in a 3:2 ratio in the presence of NH4PF6 afforded the trinuclear gold(I) complex, [Au-3(mu-dpmp)(2)Cl](PF6)(2) (6), in good yield. Complex 6 was readily transformed, by treatment with 1 equiv. of KX (X = Br, I) in a methanol/dichloromethane mixed solvent, into the analogous complexes [Au-3 (mu-dpmp)(2)X](PF6)(2) (X = Br (7), I (8)). Complexes 6-8 were characterize d by elemental analysis, IR, P-31{H-1} NMR, and W-Vis absorption spectrosco pic techniques and X-ray crystallographic analysis. Complexes 6-8 consist o f three Au(I) ions bridged by two dpmp ligands (av. Au-Au = 2.944 Angstrom (6), 2.950 Angstrom (7), 2.934 Angstrom (8)), which further interacted with a halide anion leading to a bent trinuclear core with Au-Au-Au angles 143. 46(4)degrees (6), 141.12(6)degrees (7), and 142.73(5)degrees (8). The bent trimetallic core is assumed to be retained even in solution on the basis of their spectral data. and in particular, emission spectra were entirely dif ferent depending on the halide anion; complexes 6 (X = Cl) and 8 (X = I) we re luminescent with emission band maxima at 469 and 551 nm. respectively, w hereas complex 7 (X = Br) was not luminescent. The present results demonstr ated that the structures and properties of dpmp-bridged trigold(I) complexe s were dramatically influenced by the halide anions used. (C) 2000 Elsevier Science S.A. All rights reserved.