The unusual torsion–inversion dynamics of carbodi-imide, HNCNH
- 1 January 1988
- journal article
- research article
- Published by Royal Society of Chemistry (RSC) in Journal of the Chemical Society, Faraday Transactions 2: Molecular and Chemical Physics
- Vol. 84 (9) , 1341-1363
- https://doi.org/10.1039/f29888401341
Abstract
The rotation–torsion spectrum of carbodi-imide (HNCNH) has been measured in the region from 20 GHz to 330 cm–1. Aside from a small doublet splitting (–1) detected for most of the transitions, the spectral pattern for a perpendicular band, expected for skew-chain molecules, was observed. Carbodi-imide was found to be one of the most nearly symmetric-top molecules known with the b-rotational axis parallel to the C2 symmetry axis. Molecular constants were obtained by fitting the positions of the doublet centres with Watson's Hamiltonian in S-reduction: A= 379 244.455 (27) MHz, B= 10366.940 8 (20) MHz, C= 10366.090 7 (26) MHz, κ=–0.999 995 390 (18). The analysis of the unusual dependence of the torsional splitting on Ka allowed some conclusions concerning the dynamics of carbodi-imide. The energy separation due to the cis torsional tunnelling was found to be somewhat larger than that dur to the trans torsional tunnelling. The strong dependence of the torsional splittings on Ka indicates a large rotation–HNC bending interaction affecting the barriers Vcis and Vtrans, hindering internal rotation.Keywords
This publication has 0 references indexed in Scilit: