Boronyls as Key Structural Units in Boron Oxide Clusters:  B(BO)₂^- and B(BO)₃^-

Even though BO^- is isoelectronic with CN^-, the chemistry of BO^- is relatively unknown. Here we report the first combined photoelectron spectroscopy and computational evidence that BO is a robust inorganic ligand that governs structural and electronic properties in B₃O₂^- and B₄O₃^-. Both anions yield similar and simple vibrationally resolved photoelectron spectra. Theoretical calculations reveal that B₃O₂^- possesses a linear OBBBO^- structure (D_∞h, ³Σ_g) and B₄O₃^- is a triangular B(BO)₃^- cluster (D_3h, ²A₂‘ ‘), which can be viewed as two and three boronyls bonded to a single B atom, respectively. The current finding suggests that boronyls may be key structural units in boron-rich boron oxide cluster and they can be used to design novel boronyl compounds.