η2-Alkynyl and Vinylidene Transition Metal Complexes. 8.1 Synthesis of Bimetallic Tungsten Gold Complexes by Addition of ClAuPPh3 to the Acetylide Li[(η5-C5H5)(CO)(NO)W(C⋮C−R)]

Tungsten acetylide complexes 1 [R = C(CH 3 ) 3; R = C 6 H 5; R = p -tolyl] have been found to react in THF at −60 °C with ClAuP(C 6 H 5 ) 3 to yield the bimetallic tungsten gold complexes [(η 5 -C 5 H 5 )(NO)(μ-CO)(μ-C⋮C−R)W−AuP(C 6 H 5 ) 3 ] [ 8a, R = C(CH 3 ) 3; 8b, R = C 6 H 5; 8c, R = p -tolyl] with semibridging carbonyl and alkynyl ligands. The molecular structure of 8a was determined by single-crystal X-ray diffraction analysis. Variable-temperature NMR studies of 8a showed fluxional behavior and at −80 °C the presence of three isomers.