Ab initio self-consistent field assignment of vibrational spectra of diimide, N 2H 2

Abstract

The structures and complete force fields of cis- and trans-diimide (diazene) were calculated using STO 3G and 4–31G basis sets with different approximations. The force constants obtained from these SCF wavefunctions for the trans species are compared with the most reliable experimental force fields, which are critically examined. To more accurately define and resolve the vibrational spectrum of diimide, a calculation of dipole moment derivatives was also performed. The results suggest that the torsional frequency of N 2H 2 should lie above 1300 cm −1, certainly in the spectral region of 1600–1660 cm −1.