Nickel complexes of phosphine-appended benzannulated boron heterocycles

We report the synthesis and characterization of two diphosphine nickel complexes containing 9-borafluorene (PBFIu, 9-(diisopropylphosphino)phenyl-9-borafluorene) and 9,10-dihydroboranthrene (B2P2, 9,10-bis(2-(diisopropylphosPhino)phenyl)-9,10-dihydroboranthrene) cores. Metalation of PBFlu and B2P2 with Ni(PPh3)(4) leads to the monometallic complexes (PBFIu)Ni(PPh3) and (B2P2)Ni, respectively. Cyclic voltammetry studies show a reversible redox event at similar to 0.1 V and a quasi-reversible event at ca. -3 V versus ferrocene/ferrocenium for (B2P2)Ni while (PBFlu)Ni(PPh3) features no reversible redox events. Electronic structure calculations were performed to provide further insight into the bonding in these complexes. (C) 2019 Elsevier Ltd. All rights reserved.