Acyclic Boryl Complexes of Copper(I).

Reaction of (6-Dipp)CuOtBu (6-Dipp=C{NDippCH } CH , Dipp=2,6-iPr C H ) with B (OMe) provided access to (6-Dipp)CuB(OMe) via σ-bond metathesis. (6-Dipp)CuB(OMe) was characterised by NMR spectroscopy and X-ray crystallography and shown to be a monomeric acyclic boryl of copper. (6-Dipp)CuB(OMe) reacted with ethylene and diphenylacetylene to provide insertion compounds into the Cu-B bond which were characterised by NMR spectroscopy in both cases and X-ray crystallography in the latter. It was also competent in the rapid catalytic deoxygenation of CO in the presence of excess B (OMe) . Alongside π-insertion, (6-Dipp)CuB(OMe) reacted with LiNMe to provide a salt metathesis reaction at boron, giving (6-Dipp)CuB(OMe)NMe , a second monomeric acyclic boryl, which also cuproborated diphenylacetylene. Computational interrogation validated these acyclic boryl species to be electronically similar to (6-Dipp)CuBpin.