The Microwave Spectrum and Structure of Chlorine Trifluoride

A microwave spectrometer designed for the study of the microwave spectra of corrosive fluorine compounds has been used to observe and measure a portion of the microwave spectrum of chlorine trifluoride. A number of transitions have been identified, and from these the moments of inertia and quadrupole coupling coefficients of both Cl³⁵F₃ and Cl³⁷F₃ obtained. An intensity alternation was observed showing that the ClF₃ molecule has a C_2v axis and is planar. The moments of inertia confirm this and further show that ClF₃ has a distorted ``T'' structure with one short (1.598A) and two long (1.698A) ClF bonds. The angle between the two different kinds of ClF bonds is 87°29'. The quadrupole coupling coefficients χ_aa(Cl³⁵F₃)=-81_.2 mc, χ_bb(Cl³⁵F₃)=-64_.7 mc, χ_cc(Cl³⁵F₃)=146 mc agree with the observed frequency, f(Cl³⁵F₃)=75.129₅ mc, of the pure quadrupole spectrum of ClF₃, which corresponds to an eqQ of 150 mc.