Theoretical study of structures, energetics and vibrational properties of BC 2H 5 species

Abstract

Hybrid density functional theory (B3LYP) and quadratic configuration interaction including single and double excitations (QCISD) methods with the Dunning correlation consistent polarized valence double zeta (cc-pVDZ) basis set have been used to examine the structures, vibrational spectra and stabilities of the singlet spin multiplicity molecular species with BC 2H 5 stoichiometry. Six isomers have been located. Total energies, refined at the CCSD(T)/cc-pVTZ//B3LYP/cc-pVDZ level, predict vinylborane molecule (H 2BCHCH 2, C s) to be the absolute minimum followed by the H 2CBCH 3 molecule (C s), 2.3 kcal/mol less stable. Borirane (HB(CH 2) 2, C 2v with BC 2 ring) and HBCHCH 3 (C s) molecules are calculated, respectively, to be 13.5 and 18.5 kcal/mol higher than vinylborane. The BH 3:C 2H 2 donor–acceptor complex is found about 42 kcal/mol higher than vinylborane. Ethylborine molecule BCH 2CH 3, the highest energy isomer, is predicted 45 kcal/mol above the absolute minimum. The calculated vibrational spectra for H 2BCHCH 2 and H 2CBCH 3 agree with the recent matrix isolation experiments and confirm their argon matrix IR characterization.