Acyclic Boryl Complexes of Copper(I)

Abstract

Reaction of (6‐Dipp)CuOtBu (6‐Dipp = C{NDippCH2}2CH2, Dipp = 2,6‐iPr2C6H3) with B2(OMe)4 provided access to (6‐Dipp)CuB(OMe)2 via σ‐bond metathesis. (6‐Dipp)CuB(OMe)2 was characterised by NMR spectroscopy and X‐ray crystallography and shown to be a monomeric acyclic boryl of copper. (6‐Dipp)CuB(OMe)2 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 CO2 in the presence of excess B2(OMe)4. Alongside π‐insertion, (6‐Dipp)CuB(OMe)2 reacted with LiNMe2 to provide a salt metathesis reaction at boron, giving (6‐Dipp)CuB(OMe)NMe2, a second monomeric acyclic boryl, which also cuproborated diphenylacetylene. Computational interrogation validated these acyclic boryl species to be electronically similar to (6‐Dipp)CuBpin.

Dial-a-base mechanochemical synthesis of N-heterocyclic carbene copper complexes

“…5 Moreover, the ring-expanded NHC (RE-NHC) 6-Dipp has been found to be a privileged motif in isolating and structurally characterising a wide range of interesting copper complexes. Routes to these generally start from (6-Dipp)CuO t Bu and have provided access to an isolable NHC-copper hydride dimer, 6 a range of highly stable NHC-copper boryls, 7–9 as well as a copper formimidoyl, 10 copper phosphide, 11 copper stannyl, 12 and copper germyl, 13 amongst others.…”