Vibrational spectra of cis-dimethyldiazene-d0, -1,1,1-d3, and -d6

Abstract

Gas- and solid-phase infrared spectra and liquid- and solid-phase Raman spectra of cis-dimethyldiazene-d/sub 0/, -1,1,1-d/sub 3/, and -d/sub 6/(cis-CH/sub 3/N=NCH/sub 3/,cis-CD/sub 3/N=NCH/sub 3/, and cis-CD/sub 3/N=NCD/sub 3/) have been recorded. A virtually complete assignment of the vibrational fundamentals has been made for the set of molecules with frequencies being given for all but four of the 72 fundamentals. The vibrational spectra support C/sub 2//sub v/ symmetry for the d/sub 0/ and d/sub 6/ molecules but not distinguish between the two possible conformers of this symmetry. The frequencies have been computed at the zero-order level with a potential function transferred from trans-dimethyldiazene. These predicted frequencies aided the assignments for the cis molecules and provided a basis for analyzing some of the observed frequencies. The observed spectra contain a number of features which have been interpreted as evidence of crowding between the two methyl groups in cis-dimethyldiazene. The fundamentals for the undeuterated molecule are as follows, in cm/sup -1/: (a/sub 1/) 3006,2904,1561,1438,1370,1087,861,398; (a/sub 2/) 2960,1477,1170,463,242; (b/sub 1/) 3019,2920,1430,1359,1159,935,624; (b/sub 2/) 2960,1460,935,....