Zum Rotations-Zeeman-Effekt in Molekülen mit annähernd frei drehbaren Methylgruppen/ Rotational Zeeman Effect of Molecules with Low Methyl Barriers. I. Nitromethane

Abstract

The rotational Zeeman effect of CH 3 -NO 2 , a molecule with a very low barrier to internal rotation has been studied at field strengths up to 25 kG. From the Zeeman splittings of rotational transitions in excited torsional states the “g-value of the methyl-group” was determined to be g a = +0.347 ± 0.002. This comparatively high value indicates that in nitromethane valence electrons are shifted from the C - H-bond region towards the NO 2 -group, an explanation which is backed by the results of CNDO/2 and INDO-calculations.