Theoretical study of structures, energetics and vibrational properties of BC 2H 3 species

Abstract

Theoretical study using self-consistent field (SCF), hybrid density functional theory (B3LYP) and quadratic configuration interaction including single and double excitations (QCISD) with the Dunning correlation consistent polarized valence double zeta (cc-pVDZ) basis set have been used to examine the structures and vibrational properties of the singlet species with BC 2H 3 stoichiometry. Relative stabilities are estimated at the CCSD(T)/cc-pVTZ level using QCISD/cc-pVDZ optimized geometries. Five species corresponding to different nuclear arrangements have been studied. The absolute minimum corresponds to the 2 π aromatic borirene molecule (HBC 2H 2 with a BC 2 ring). Ethynylborane (H 2BCCH, C 2 v ) and borallene (H 2CCBH, C 2 v ) are respectively 6.4 and 24.3 kcal/mol higher. Vinylborine (C 2H 3B, C s ) and H 2CBCH (C 2 v ) are much less stable, 46.2 and 49.1 kcal/mol respectively higher than borirene. The calculated vibrational spectra agree with experiment and confirm the infrared matrix characterization of the three most stable species.