Identification of diborane(4) with bridging B–H–B bonds

Abstract

The irradiation of diborane(6) dispersed in solid neon at 3 K with tunable far-ultraviolet light from a synchrotron yielded a set of IR absorption lines, the pattern of which implies a carrier containing two boron atoms. According to isotope effects and quantum-chemical calculations, we identified this new species as diborane(4), B₂H₄, possessing two bridging B–H–B bonds. Our work thus establishes a new prototype, diborane(4), for bridging B–H–B bonds in molecular structures.