Vibrational Spectra and Thermodynamic Properties of ClF3 and BrF3

The Raman and infrared spectra of ClF3 and BrF3 have been studied. The spectra of ClF3 give strong support for a planar T‐shaped molecular model. The spectra of BrF3 are less complete but are sufficiently similar to that of ClF3 to confirm a like shape for this molecule. The fundamental vibrational frequencies of ClF3 observed for the vapor are 326(a1), 364(b2), 434(b1), 528(a1), 703(b1), and 752(a1) cm‐1. S0 for ClF3, calculated statistically at the boiling point, 11.75°C, is 66.60 cal mole‐1 deg‐1 compared to the value of 67.04 obtained from a revised calculation of this quantity from available thermal data. For BrF3 only two fundamental frequencies were observed in the vapor, 613(b1) and 674(a1) cm‐1; the others were estimated by a normal coordinate calculation. S0 for BrF3 calculated statistically is 70.86 cal mole‐1 deg‐1 at 43.11°C compared to a value of 71.90 calculated from available thermal data. Tables of the thermodynamic functions of ClF3 and BrF3 from 250 to 1000°K are given.

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