Investigations on the microwave spectrum of meta-di-fluoro-benzene

Abstract

The microwave spectrum of m-C₆¹²H₄F₂ has been measured from 18·0 to 25·0 GHz with wavemeter and frequency standard techniques, using a Stark modulated gas-absorption, microwave spectrometer. The analysis of the spectrum is based on the rigid asymmetric top theory; the rotational constants and the principal moments of inertia were determined and a preliminary structure of the molecule is given. The results are in agreement with the assumed planarity of the molecule and with normal values of bond distances. The rotational constants are: A = 3739·97 ± 0·3 MHz., B = 1734·95 ± 0·1 MHz., C = 1185·48 ± 0·1 MHz. The inertia defect obtained is I_c  I_a  I_b = −0·11 amuA².