Theoretical investigation of isomeric structures of B 2 O 3 . Kinetic and thermodynamic study of the transformation of boric oxide to metaboric acid HBO 2 . Complexation of HBO 2 : from dimer to hexamer

In this study, Density Functional Theory was adopted. Isomeric structures of boric oxide B2O3 were investigated at B3LYP/6-311G++(d,p), M052X, M062X, M08HX, M11/6-311G++(d,p) levels of theory. For validation of stable states, optimisation was performed using the correlated coupled cluster with single, double, and perturbative triple excitations (CCSD(T)) method in conjunction with the augmented correlation-consistent polarisation valence Double Zeta (aug-cc-pVDZ) (AVDZ) basis sets. Intrinsic Reaction Coordinates (IRCs) calculations were carried out to give kinetics of reactions B2O3+H2O ⇌ 2HBO2, B2O3+HCl ⇌ HBO2 + OBCl. Complexation of HBO2 was considered using B3LYP-D3, B97-D, MN15 and wB97X-D dispersion-corrected functionals. Counterpoise-corrected complexation energies as well as frontier orbital HOMO-LUMO energy gaps of (HBO2)n (n = 2, 3, 4, 5, 6) clusters were derived in order to study their stability owed to hydrogen bonds.