The computational study on the structural and force field changes, caused by the conversion of dicyanamide into the azanion

The structural and force field changes, caused by the conversion of the dicyanamide molecule HN(CN)2 into the corresponding azanion −N(CN)2, have been studied by ab initio and DFT 6-31++G(d,p) force field calculations, as well as (for the anion only) on the basis of literature experimental data. The theoretical vibrational and structural indices of the anion are in agreement with those obtained by vibrational spectroscopy and X-ray diffraction analysis. According to MP2 and B3LYP calculations, the conversion of dicyanamide into the azanion results in 83-122 cm−1 decreases in the cyano stretching frequencies (average of νs and νas), 6.3-8.3 fold increases in the corresponding IR integrated intensities (total values) and other essential spectral changes. Again according to the calculations, ca. 0.6 e− of the new (azanionic) charge are delocalized over the two CN groups and ca. 0.4 e− of it remain localized at the azanionic center.