Bridging 1,2-Bis(diphenylphosphino)methane Ligands Facilitate the Formation of Binuclear Complexes with Both Two-Coordinate and Three-Coordinate Gold(I) Ions.

Five new crystalline gold(I) complexes β-Au(μ-dppm)Br·2CHCl (), [Au(μ- dppm)Br]Br·2CHCl (), Au(μ-dppm)Br (), Au(μ-dppm)Cl·3CHCl () and [Au(μ-dppm)]Cl(AsF)·2CHCl () (where dppm is bis(diphenylphosphino)methane) have been prepared and structurally characterized by single crystal X-ray diffraction. Colorless β-Au(μ-dppm)Br·2CHCl () has centrosymmetric structure with two three-coordinate gold(I) ions held in close proximity by the dppm ligands. Crystals of [Au(μ- dppm)Br]Br·2CHCl (), Au(μ-dppm)Br (), and Au(μ-dppm)Cl·3CHCl () have a cation with an unusual arrangement that binds a two-coordinate gold(I) ion to a three-coordinate gold(I) ion through an aurophilic interaction. Whereas Au(μ-dppm)Cl(BPh)·3CHCl () has a chloride ion bound to only one of the gold ions in the complex, [Au(μ-dppm)]Cl(AsF)·2CHCl () has an ion paired chloride ion that is symmetrically disposed between the two gold ions at a rather long distance. Each complex displays luminescence under UV irradiation.