Sigma- and pi-bond strengths in main group 3-5 compounds

Daniel J Grant; David A Dixon

doi:10.1021/jp065085q

Sigma- and pi-bond strengths in main group 3-5 compounds

J Phys Chem A. 2006 Nov 30;110(47):12955-62. doi: 10.1021/jp065085q.

Authors

Daniel J Grant¹, David A Dixon

Affiliation

¹ Department of Chemistry, Shelby Hall, The University of Alabama, P.O. Box 870336, Tuscaloosa, AL 35487-0336, USA.

PMID: 17125312
DOI: 10.1021/jp065085q

Abstract

The sigma- and pi-bond strengths for the molecules BH2NH2, BH2PH2, AlH2NH2, and AlH2PH2 have been calculated by using ab initio molecular electronic structure theory at the CCSD(T)/CBS level. The adiabatic pi-bond energy is defined as the rotation barrier between the equilibrium ground-state configuration and the C(s)symmetry transition state for torsion about the A-X bond. We also report intrinsic pi-bond energies corresponding to the adiabatic rotation barrier corrected for the inversion barrier at N or P. The adiabatic sigma-bond energy is defined as the dissociation energy of AH2XH2 to AH2 + XH2 in their ground states minus the adiabatic pi-bond energy. The adiabatic sigma-bond strengths for the molecules BH2NH2, BH2PH2, AlH2NH2, and AlH2PH2 are 109.8, 98.8, 77.6, and 68.3 kcal/mol, respectively, and the corresponding adiabatic pi-bond strengths are 29.9, 10.5, 9.2, and 2.7 kcal/mol, respectively.