Transition-metal-like bonding behaviors of a boron atom in a boron-cluster boronyl complex [(η⁷-B₇)-B-BO].

ABSTRACT: Boron displays many unusual structural and bonding properties due to its electron deficiency. Here we show that a boron atom in a boron monoxide cluster (B₉O^-) exhibits transition-metal-like properties. Temperature-dependent photoelectron spectroscopy provided evidence of the existence of two isomers for B₉O^-: the main isomer has an adiabatic detachment energy (ADE) of 4.19 eV and a higher energy isomer with an ADE of 3.59 eV. The global minimum of B₉O^- is found surprisingly to be an umbrella-like structure (C _6v, ¹A₁) and its simulated spectrum agrees well with that of the main isomer observed. A low-lying isomer (C _s, ¹A') consisting of a BO unit bonded to a disk-like B₈ cluster agrees well with the 3.59 eV ADE species. The unexpected umbrella-like global minimum of B₉O^- can be viewed as a central boron atom coordinated by a η⁷-B₇ ligand on one side and a BO ligand on the other side, [(η⁷-B₇)-B-BO]^-. The central B atom is found to share its valence electrons with the B₇ unit to fulfill double aromaticity, similar to that in half-sandwich [(η⁷-B₇)-Zn-CO]^- or [(η⁷-B₇)-Fe(CO)₃]^- transition-metal complexes. The ability of boron to form a half-sandwich complex with an aromatic ligand, a prototypical property of transition metals, brings out new metallomimetic properties of boron.

SUBMITTER: Tian WJ 

PROVIDER: S-EPMC8208299 | biostudies-literature |

REPOSITORIES: biostudies-literature