Vibrational spectra and structure of nitrogen containing molecules—III. Acetone azine and acetone azine- d12

Abstract

The i.r. spectra of (CH 3) 2CNNC(CH 3) 2 and (CD 3) 2CNNC(CD 3) 2 have been studied from 4000 to 300 cm −1 in all three physical states. Absorption spectra for the polycrystalline samples were also obtained down to 33 cm −1. Raman spectra for liquid and crystalline acetone azine and acetone azine- d 12 were recorded between 4000 and 100 cm −1. Since mutual exclusion was observed for the i.r. and Raman bands assigned to the skeletal modes of acetone azine, the spectral data have been interpreted in terms of C 2 h molecular symmetry. An assignment of the fundamental vibrations is based upon the observed isotopic shift ratios, depolarization measurements, relative band intensities and positions. The methyl torsional modes were assigned to bands at 235 and 215 cm −1, respectively, in the Raman spectrum of crystalline acetone azine. The frequencies associated with the CN and NN stretching modes of acetone azine suggest the π electrons may not be localized and this observation is consistent with the bond orders for the CN (1.9) and NN (1.5) groups calculated from simple molecular orbital theory. The results of the present study are compared with the data recently reported for tetramethylhydrazine and tetramethyltetrazine.