Reactivity of Gold and Copper Acetylide with a Secondary Borane

Abstract

Gold(I) triphenylphosphine phenylacetylide reacts with bis(1-methyl-ortho-carboranyl)borane to give a hydroboration product that is best described as an η²-1-borataallene gold complex. Contrarily, the analogous reaction with the copper acetylide undergoes transmetallation to furnish an alkynylborate with the CuPPh₃⁺ moiety bound to the alkyne and a hydride bridging boron to copper. The compounds were analyzed by single crystal X-ray diffraction and DFT computations that rationalize the unusual bonding arrangements.