Spectroscopic studies of molecular interactions involving 2,6-diethylaniline and N-ethylaniline donors and iodine as an electron acceptor in different solvents

The charge-transfer complexes of 2,6-diethylaniline (DEA) and N-ethylaniline (NEA) with iodine, as a typical or-acceptor were studied spectrophotometrically in chloroform, dichloromethane and carbontetrachloride solutions. Spectral data, formation constants and effect of solvent have been determined. Spectral characteristics and formation constants are discussed in the terms of donor molecular structure and solvent polarity. The stoichiometry of the complexes was established to be 1:1. For this purpose, optical data were subjected to the form of the Rose-Drago equation for 1:1 equilibria. The formation constant (K-AD) and molar absorptivities (epsilon(lambda)) of complexes were determined by least square method. Electronic absorption spectra of the anilines were measured in different solvents. Spectral data were reported and band maxima were assigned to the appropriate molecular orbital transitions. Quantum chemical calculations were performed with the aid of the Gaussian 98 set of programs. The structure were fully optimized at MP2 level using 6-31 + G** basis set. The computations show that DEA is not planner with the amino group having a somewhat sp(3) hybridization-like character. (c) 2006 Elsevier B.V. All rights reserved.