Synthesis of a hydrogen-bridged tetraborane(6): a substituent effect of a diaminoboryl group toward the B-B multiple bond character

A hydrogen-bridging tetraborane(6) was synthesized from boryllithium, a boron nucleophile, in three steps. The structural and spectroscopic analyses of the tetraborane(6) revealed σ-donor and π-acceptor effects of diaminoboryl substituents toward the central B-B moiety having a multiple bond character. DFT calculations also supported the experimentally observed substituent effect of the boryl group. A hydrogen-bridging tetraborane(6) was synthesized from boryllithium, a boron nucleophile, in three steps.