VIBRATIONAL ANALYSIS OF 1,3,3-TRINITROAZETIDINE USING MATRIX-ISOLATION INFRARED-SPECTROSCOPY AND QUANTUM-CHEMICAL CALCULATIONS

Infrared spectra of 1,3,3-trinitroazetidine (TNAZ), (O2N)(2)-C(CH)(2)N -NO2, were obtained for samples evaporated from a Knudsen Cell and cod eposited with argon on a 15 K IR window. Spectra of matrix-isolated TN AZ and isotopically labeled TNAZ are used to assign 24 of the 45 funda mental molecular vibrations. Comparisons among experimental spectra an d spectra calculated using Hartree-Fock (HF), second-order Moller-Ples set theory (MP2) and three density functional theory (DFT) methods ind icate that DFT gives a more accurate vibrational description than MP2 or HF. The DFT approach was further explored using the BP86 and the hy brid B3P86 and B3LYP methods, Overall best results were obtained with BP86 and B3LYP.