|
Internet Electronic Journal of Molecular Design - IEJMD, ISSN 1538-6414, CODEN IEJMAT
| ABSTRACT - Internet Electron. J. Mol. Des. August 2006, Volume 5, Number 8, 471-478 |
Ab initio Investigation of the Substituant Effect
of the Alane Complexes
Mustapha Cherkaoui and Abderrahim Boutalib
Internet Electron. J. Mol. Des. 2006, 5, 471-478
|
Abstract:
The binding interactions between an electron pair donor
(Lewis base) and an electron pair acceptor (Lewis acid)
play an important role in many chemical processes. The
reaction course of numerous reactions takes place with
formation of donor-acceptor adducts as intermediates. The
geometrical parameters are sensitive to intra- and
inter-molecular interactions; hence they can indicate and
characterize these processes. The strength of the adduct
bond is generally lower than that of a typical covalent
bond. The present study reports the quantum chemistry
analysis of the X3AlY(CH3)3
(X = H, F, and Cl; Y = N, P,
and As) donor-acceptor complexes. All calculations were
performed with the ab initio method at the MP2 level of
theory. For all complexes the staggered conformation
(C3v symmetry) is found to be favored.
The MP2/6-311++G(df,p)
energetic results show that the stability
decreases when going from nitrogen to arsenic for all
complexes. The NBO partitioning scheme shows that the
unusual shortening of the P-C and As-C bond lengths upon
complexation is due to an increasing s character and
Wiberg bond index in these bonds. The calculated
complexation energies corrected with the BSSE corrections
show that the F3AlY(CH3)3
(Y = N, P, and As) complexes
are more stable than Cl3AlY(CH3)3
and H3AlY(CH3)3 ones.
The NBO partitioning scheme analysis shows that there is
no correlation between the stability and the charge transfer.
|