THEORETICAL-STUDY OF STRUCTURES, ENERGETICS AND VIBRATIONAL PROPERTIES OF BC2H3 SPECIES

Theoretical study using self-consistent field (SCF), hybrid density fu nctional theory (B3LYP) and quadratic configuration interaction includ ing single and double excitations (QCISD) with the Dunning correlation consistent polarized valence double zeta (cc-pVDZ) basis set have bee n used to examine the structures and vibrational properties of the sin glet species with BC2H3 stoichiometry. Relative stabilities are estima ted at the CCSD(T)/cc-pVTZ level using QCISD/cc-pVDZ optimized geometr ies. Five species corresponding to different nuclear arrangements have been studied. The absolute minimum corresponds to the 2 pi aromatic b orirene molecule (HBC2H2 with a BC2 ring). Ethynylborane (H2BCCH, C-2v ) and borallene (H2CCBH, C-2v) are respectively 6.4 and 24.3 kcal/mol higher. Vinylborine (C2H3B, C-s) and H2CBCH (C-2v) are much less stabl e, 46.2 and 49.1 kcal/mol respectively higher than borirene. The calcu lated vibrational spectra agree with experiment and confirm the infrar ed matrix characterization of the three most stable species. (C) 1998 Elsevier Science B.V. All rights reserved.