Theoretical Study of the Binding of Silane (SiH₄) with Borane (BH₃), Diborane (B₂H₆), and Boron Trichloride (BCl₃): The Role of Core–Electron Correlation

Abstract

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.

Structural Characterization of a Boron(III) η2-σ-Silane-Complex

“…Intriguingly, theoretical studies by Kim and Gordon suggested that Lewis acid BH 3 could form Type II σ-complexes with SiH 4 in gas phase in which one of the H–Si bond is substantially activated. Recently Piers successfully isolated a borane-HSiEt 3 adduct with a borole derivative, 1,2,3-tris­(pentafluorophenyl)-4,5,6,7-tertafluoro-1-boraindene .…”

Systematic Study of the Basis Set Superposition Error in Core–Electron Correlation Effects

“…For comparison, a-cc-pVTZ single point energies are also computed. Results and literature values are collected in Table .…”

“… a Shorter Si–B bond. b Based on MP2­(AE*)/a-cc-pwCVTZ geometry. c Taken from ref , AE* results corresponds to the partial frozen-core treatment. …”

“…In contradiction to this common experience, Xu et al found a significant change by including CEC into their computations even in the qualitative outcome of their investigation of silane complexes with borane, diborane, and boron trichloride . To compute their results they applied the aug-cc-pVTZ and aug-cc-pVQZ basis sets.…”

“…In contradiction to this common experience, Xu et al found a significant change by including CEC into their computations even in the qualitative outcome of their investigation of silane complexes with borane, diborane, and boron trichloride. 11 To compute their results they applied the aug-cc-pVTZ and aug-cc-pVQZ basis sets. These valence basis sets are not meant to describe CEC effects, and the insufficiency of the correlation consistent basis set families, 12,13 called (aug-)cc-pVXZ, motivated the development of new families of correlation consistent basis sets where CEC was taken into account for the optimization.…”