Spectroscopic study on deuterated benzenes. I. Microwave spectra and molecular structure in the ground state

摘要

We observed microwave absorption spectra of some deuterated benzenes and accurately determined the rotational constants of all H/D isotopomers in the ground vibrational state. Using synthetic analysis assuming that all bond angles are 120 degrees, the mean bond lengths were obtained to be r(0)(C-C) = 1.3971 angstrom and r(0)(C-H) = r(0)(C-D) = 1.0805 angstrom. It has been concluded that the effect of deuterium substitution on the molecular structure is negligibly small and that the mean bond lengths of C-H and C-D are identical unlike small aliphatic hydrocarbons, in which r0(C-D) is about 5 m angstrom shorter than r(0)(C-H). It is considered that anharmonicity is very small in the C-H stretching vibration of aromatic hydrocarbons. (C) 2015 AIP Publishing LLC.