UVPES and ab initio molecular orbital studies on the electron donor-acceptor complexes of bromine with methylamines

Ammal, Salai Cheettu S and Ananthavel, SP and Venuvanalingam, P and Hegde, MS (1997) UVPES and ab initio molecular orbital studies on the electron donor-acceptor complexes of bromine with methylamines. In: Journal of Physical Chemistry A, The, 101 (6). pp. 1155-1159.

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Abstract

The He I photoelectron spectra of bromine, methylamine, and their complex have been obtained, and the spectra show that lone-pair orbital energy of nitrogen in methylamine is stabilized by 1.8 eV and the bromine orbital energies are destabilized by about 0.5 eV due to complexation. Ab initio calculations have been performed on the charge-transfer complexes of Br-2 with ammonia and methyl-, dimethyl-, and trimethylamines at the 3-21G*, 6-311G, and 6-311G* levels and also with effective core potentials. Calculations predict donor and acceptor orbital energy shifts upon complexation, and there is a reasonable agreement between the calculated and experimental results. Complexation energies have been corrected for BSSE. Frequency analysis has confirmed that ammonia and trimethylamine form complexes with C-3v symmetry and methylamine and dimethylamine with C-s symmetry. Calculations reveal that the lone-pair orbital of nitrogen in amine and the sigma* orbital of Br-2 are involved in the charge-transfer interaction. LANL1DZ basis seems to be consistent and give a reliable estimate of the complexation energy. The computed complexation energies, orbital energy shifts, and natural bond orbital analysis show that the strength of the complex gradually increases from ammonia to trimethylamine.

Item Type:	Journal Article
Publication:	Journal of Physical Chemistry A, The
Publisher:	American Chemical Society
Additional Information:	Copyright of this article belongs to American Chemical Society.
Department/Centre:	Division of Chemical Sciences > Solid State & Structural Chemistry Unit
Date Deposited:	22 Jun 2011 07:10
Last Modified:	22 Jun 2011 07:10
URI:	http://eprints.iisc.ac.in/id/eprint/38564

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