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Raman spectra of gases. XXV —nitrocyclopropane
Author(s) -
Durig J. R.,
Sun F. Y.,
Li Y. S.,
Bush S. F.
Publication year - 1982
Publication title -
journal of raman spectroscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.748
H-Index - 110
eISSN - 1097-4555
pISSN - 0377-0486
DOI - 10.1002/jrs.1250130316
Subject(s) - chemistry , raman spectroscopy , cyclopropane , excited state , substituent , molecule , internal rotation , atomic orbital , spectral line , ring (chemistry) , atomic physics , computational chemistry , stereochemistry , physics , electron , organic chemistry , mechanical engineering , quantum mechanics , astronomy , optics , engineering
The Raman spectrum of gaseous nitrocyclopropane, cC 3 H 5 NO 2 has been recorded from 3500 to 30 cm −1 . The interesting internal NO 2 torsion was observed at 85±2cm −1 from which a barrier to internal rotation in the vapor state of 1680±70 cm −1 (4.8±0.2 kcal mol −1 ) was calculated. It is shown that this torsional frequency is consistent with the relative intensities of the vibrational excited states in the microwave spectrum. This barrier value is compared to those for several other NO 2 substituted hydrocarbons as well as for the corresponding isoelectronic BF 2 substituted molecules. The high barrier value supports the structural arguments that there is significant pseudo‐conjugation between the cyclopropane ring orbitals and the substituent NO 2 group. A revised vibrational assignment is presented which is compared to the one previously given for the isoelectronic molecule, c ‐C 3 H 5 BF 2 , as well as for c ‐C 3 H 5 BCI 2 .