A Gold(I)-Acetylene Complex Synthesised using Single-Crystal Reactivity.

Using single-crystal to single-crystal solid/gas reactivity the gold(I) acetylene complex [Au(L1)(η 2 -HC≡CH)][BAr F 4 ] is cleanly synthesized by addition of acetylene gas to single crystals of [Au(L1)(CO)][BAr F 4 ] [L1=tris-2-(4,4'-di-tert-butylbiphenyl)phosphine, Ar F =3,5-(CF 3 ) 2 C 6 H 3 ]. This simplest gold-alkyne complex has been characterized by single crystal X-ray diffraction, solution and solid-state NMR spectroscopy and periodic DFT. Bonding of HC≡CH with [Au(L1)] + comprises both σ-donation and π-backdonation with additional dispersion interactions within the cavity-shaped phosphine.