Conformational study of 1,2-diaminoethane by combined ab initio MO calculations and Raman spectroscopy

A conformational analysis of the linear polyamine 1,2-diaminoethane was performed by both Raman spectroscopy and ab initio SCF-MO methods (with and without inclusion of water solvent effects). Ten different conformers were detected by ab initio calculations, the most stable ones being TGG' and GGG'. When considering the solvent, the conformations having a higher dipole moment were found to be favoured over the less polar ones. The Raman spectra of this amine obtained for the pure liquid, the aqueous solution and the solid sample, allowed to conclude that its conformational preferences are determined by the relative importance of intra- versus intermolecular hydrogen bonds. (C) 1999 Elsevier Science B.V. All rights reserved.