Theoretical study of structures, energetics and vibrational properties of BC2H3 species Original Research Article

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 BC2H3 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 (HBC2H2 with a BC2 ring). Ethynylborane (H2BCCH, C2v) and borallene (H2CCBH, C2v) are respectively 6.4 and 24.3 kcal/mol higher. Vinylborine (C2H3B, Cs) and H2CBCH (C2v) 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.