Infrared spectra of some isotopomers of isopropylamine: A theoretical study

The normal-mode frequencies and the corresponding vibrational assignments o f some isotopomers of isopropylamine are examined theoretically using the G aussian 94 set of quantum chemistry codes at the MP2 level of theory using a 6-311g** basis set. In particular deuteration of the NH2 hydrogen atoms a s well as the deuteration of the CH3 hydrogen atoms, the alpha-CH hydrogen atom, and various combinations of deuteration of isopropylamine are examine d. Correction factors for predominant vibrational motions are reported and compared for a number of isotopomers of s-trans- and gauche-isopropylamine. Comparison of theoretically predicted infrared spectra with experimental s pectra is made for isotopomers for which experimental data exist. Enthalpy, entropy, and Gibbs free energy changes are considered for the trans --> ga uche transformation. An amino torsional potential is deduced and barrier he ights are calculated for the brans --> gauche, gauche --> trans, and gauche --> gauche transformations. (C) 1999 John Wiley & Sons, Inc. Int J Quant C hem 72: 109-126, 1999.