Theoretical and spectroscopic study of asymmetric methyl rotor dynamics in gaseous partially deuterated nitromethanes
摘要:
Ab-initio calculations have been performed at the HF/6-31G** and HF/6-31++G(d,p) levels to study the conformational dependence of the geometry and the vibrational frequencies of three hydrogen/deuterium (d0, d1, d2) isotopomers of nitromethane. The Raman gas-phase spectra of these compounds are also presented. They compare well with the infrared ones and the theoretical prediction. The calculated overall zero-point vibrational energy of both d1 and d2 isotopomers presents an angular dependence of the form V2 cos(2theta) + V4 cos(4theta). It contributes significantly to the methyl torsion potential and causes two different equilibrium positions for the d1 (eclipsed) and d2 (staggered) methyl groups. The vibrational origin of the V2 and V4 pseudopotential terms of the rotational potential of the partially deuterated methyl groups is thus confirmed. The close correspondence between calculated and experimental results shows that theoretical calculations can be a convenient alternative to analyze the lone CH or CD stretching spectra of the partially methyl groups.
A practical and efficient continuous-flow system was developed for the synthesis of site-selectively deuterium-labeled β-nitroalcohols by using the tertiary amine-functionalized basic anion exchang...
Isomerizations of the Nitromethane Radical Cation in the Gas Phase
作者:Helge Egsgaard、Lars Carbea、Susanne Elbel
DOI:10.1002/bbpc.19860900411
日期:1986.4
AbstractThe concurrent isomerizations of the nitromethane radical cation to aci‐nitromethane and methylnitrite isomers, respectively, has been established based on metastable ion studies and collision activation mass spectrometry. The energy diagram for the ionized nitromethane/aci‐nitromethane tautomeric system has been determined; the aci‐nitromethane tautomer was found to be the more stable species by ca. 0.95 eV. Attempts to generate the neutral gaseous aci‐nitromethane tautomer by low pressure pyrolysis are summarized.
Production of the nitromethane aci ion by static high pressure
作者:Ray Engelke、David Schiferl、C. B. Storm、William L. Earl
DOI:10.1021/j100334a062
日期:1988.11
CROWELL, T. I., J. ORG. CHEM., 1983, 48, N 19, 3294-3297