Theoretical study of the binding of silane (SiH4) with borane (BH3), diborane (B2H6), and boron trichloride (BCl3): the role of core-electron correlation.

Equilibrium structures and energies of gas-phase molecular complexes SiH(4)···BH(3), SiH(4)···B(2)H(6), and SiH(4)···BCl(3) were determined using second-order Møller-Plesset perturbation theory (MP2) and the aug-cc-pVTZ basis set, with and without explicit core electron correlation. Single-point energies were calculated for the MP2-optimized structures using MP2 with the aug-cc-pVQZ basis set and using coupled cluster theory (CCSD(T)) with both the aug-cc-pVTZ and the aug-cc-pVQZ basis sets to extrapolate to the complete basis set (CBS). Partition functions were calculated using the harmonic oscillator/rigid rotorapproximation at the MP2/aug-cc-pVTZ level of theory. The explicit core electron correlation is demonstrated to have significant impact on the structures and binding energies and binding enthalpies of these complexes. The binding enthalpies were obtained at various temperatures ranging from 0 K to the dissociation temperatures of the complexes. The potential energy surfaces of the three complexes were explored, and no transition states were found along the pathways from separated species to the complexes.