Acetylenephosphino gold(I) derivatives:: structure, reactivity and luminescence properties

We have synthesised the acetylenephosphino gold(I) derivatives, AuX(PPh2CCH) (X=Cl, Br, I, C6F5). X-Ray diffraction studies show that the chloro derivative is a dimer connected by two short hydrogen bonds from the acetylenic hydrogen to chlorine, whilst the iodo derivative is also a dimer because of a gold-gold interaction of 3.0625(9) Angstrom. The crystal structure of the pentafluorophenyl derivative shows the presence of intermolecular hydrogen bonds Au....H (3.07 Angstrom, 143degrees), also from the acetylenic hydrogen, which link the molecules into chains. The possibility of preparing alkynyl derivatives has been investigated but only complex [Au(C6F5)(PPh2CC)Au(C6F5)]-[N(PPh3)(2)] 6 has been obtained in a pure state. Complex 6 luminesces at room temperature in the solid state, and all the complexes are luminescent at 77 K with excitation maxima in the range 292-335 nm and emission maxima between 445 and 533 nm.