Reactivity of Organogold Compounds with B(C6F5)3: Gold-Boron Transmetalation via σ-B/π-Au Species

The reactions of gold-acetylides with B(C6F5)(3) afford alkynyl borate species and cationic pi-coordinated gold complexes. The analogous reactions with aryl gold species generate gem-diaurated compounds containing a borate counteranion. These new sigma-B/pi-Au alkynyl borate complexes can be employed as active catalysts in homogeneous catalysis and represent a new silver-free activation pathway. The new alkynyl borate species are fully characterized, and the alkyne fragments are shown to be bound in a sigma-B/pi-Au fashion. Upon prolonged heating, these compounds undergo a slow C6F5 group transfer to gold affording LAuC6F5 species.