A Diborylcarbazolyl Ligand for Stabilizing Low-Coordinate and Low-Valent Metal Complexes

We report the synthesis of a novel ligand L (3,6-di-tert-butyl-1,8-bis(dimesitylboryl)carbazolide) based on a carbazolyl scaffold bearing two sterically demanding boryl groups at the 1,8-positions. This diborylcarbazolyl framework effectively supports a range of transition metal complexes, including two-coordinate halide complexes LMIICl [M = Fe (2), Co (3), and Zn (4)], trinuclear complex (LCr)₂(CrCl4) (5), and pseudo-one-coordinate complexes LMI [M = Ni (6) and Cu (7)]. Coinage metal complexes derived from L exhibit a preference for two-coordinate geometries, as demonstrated by the isolation of LMPPh3 [M = Ag (8) and Au (9)] and LCu(DMAP) (10).