Microwave spectrum and structure of nitromethane

Abstract

The microwave spectra of nitromethane and five isotopic species have been investigated Groundstate moments of inertia for the rn = 0 internal rotation state have been used to derive the following structure :Nuclear spin weightings for various I K--m I states, derived using non-rigid group theory, have been confirmed by relative intensity measurements in the microwave spectra. The same theory has been used to explain the unusually large increase (0.060 a.m.u. A") in the inertial defect of CD3N02.The structure and bonding of nitromethane is compared with some related molecules. The structure of the nitro group in nitromethane is shown to fit a series of NOa compounds, between NO; and NO;, where the parameters vary according to the electronegativity of the attached grouping.

Theoretical and spectroscopic study of asymmetric methyl rotor dynamics in gaseous partially deuterated nitromethanes

“…The 6-31G** calculation gives the same qualitative answers as those already found with lower level basis sets.27-29 The theoretical fully optimized stable configuration (total energy 243.666 887 1 Hartrees) is found to have a methyl group hydrogen staggered relative to the CNOl plane and presents a certain nonplanarity of the CNOlO2 moiety, the corresponding angle between the C-N bond and the NO102 plane being 1.7O, similar to that found with the 6-31G basis.28 The energy differenceof 0.006 kcal/mol between the staggered and eclipsed conformations is lower than those previously calculated with lower basis sets (0.01-0.03 kcal/ Though this energy difference is not significant, it can be noted that it is equal to the measured rotational barrier of nitromethane. 21 Geometrical parameters for both staggered and eclipsed fully optimized forms are given in the column d of Table I Table I). In order to decrease the number of optimized parameters and to keep a C, molecular symmetry, we have constrained the CNO102 moiety to be planar (column e of Table I).…”

Theoretical study of nitro–nitrite rearrangement of CH3NO2

“…The angle between the CN bond and the NO2 plane is 1 .go. Results are presented for the cis staggered isomer of methyl nitrite, which has been shown by experiment (16) and calculations (8) to be the lowest energy form. In this form, the four heavy atoms and the hydrogen labeled H1 are strictly coplanar.…”

The Adsorption of Nitromethane on the Au (111) Surface

“…The basis set chosen combined with the B3LYP method were proven to be sufficient enough to yield geometries in good agreement both with experimental data and with values computed with the, in principle, more accurate CCSD(T) method [24]. [32]. The maximum numerical deviations from the experimental values are inferior to 0.01 Å and 1.0° for bond lengths and bond angles, respectively.…”