At the intersection of X- and Z-type ligands: an inverted ligand field in carbene-supported borylnickel complexes

Abstract

The first examples of NHC-supported borylnickel complexes have been accessed via the reaction of a phosphine-tethered carbene-bromoborane adduct and a Ni(0) source. DFT calculations and Ni K- and L-edge XANES data indicate that there is significant Ni(0) character in the resulting complexes, and that the boryl ligand in this case is best regarded as a Z-type acceptor ligand. Reactivity studies of this novel complex have found an unprecedented insertion product with an aryl isocyanide forming an 8-membered metallocycle, and a Ni abnormal-carbene complex has also been accessed from an analogous reaction with a chloroborane precursor.