Normal Coordinate Treatments and Calculated Thermodynamic Properties of Phosphoryl Chloride, Thiophosphoryl Chloride, and Phosphoryl Fluoride

Abstract

The infrared and Raman spectra for phosphoryl chloride, thiophosphoryl chloride, and phosphoryl fluoride were collected and examined for the most probable values for the wave numbers, intensities, and depolarization factors. The data are as follows: The Raman displacements Δσ in cm^—1, the relative intensities I, and the depolarization factors ρ are for POCL₃: Δσ(1)ρ = 192.85 (8) 0.83, 267.39 (6) 0.64, 337.44 (7) 0.81, 486.24 (10) 0.05, 581.2 (3) 6/7, and 1289.9 (5) 0.04; for PSCl₃: 172 (5) 6/7, 247 (7) 6/7, 247 (calculated) 430 (10) 0.1, 538 (1) 6/7, and 753 (1) P; and for POF₃: 337 (w) 6/7, 476 (m) 6/7, 483 (from infrared) P, 875 (s) 0.05, 982 (vw) 6/7, and 1395 (m) 0.1. As for the infrared spectral data, those of G. Cilento et al., were used for PSCl₃, and those of Gutowsky and Liehr were used for POF₃. No published infrared spectral data were found for POCl₃. Also normal coordinate treatments were conducted for POCl₃, PSCl₃, POF₃, and PSF₃ on the basis of a model having C_3v symmetry. The normal coordinate treatments gave the listed wave numbers as fundamentals and lend support for the 247 cm^—1 band for PSCl₃ and 483 cm^—1 band (observed in the infrared and assigned as fundamental by Gutowsky and Liehr) for POF₃ as the missing Raman bands. Moreover, the F matrix elements obtained for these molecules were determined in such a manner that those potential constants for the PCl₃ group had nearly the same values in both POCl₃ and PSCl₃, those for the PF₃ group had nearly the same values in both POF₃ and PSF₃, the one for the PO group had nearly the same value in both POCl₃ and POF₃, and the one for the PS group had nearly the same value in both PSF₃ and PSCl₃. The potential constants determined had the following values in md/A: For POCl₃, f_PO=9.890, f_PCl=2.466, f_PClPCl=0.399, for PSCl₃, f_PS=0.030, f_PCl=2.466, f_PClPCl=0.399; for POF₃, f_PO=9.890, f_PF=5.633, f_PFPF=0.483, and for PSF₃, f_PS=2.9694, f_PF=5.333, f_PFPF=0.183. Finally, the values of the thermodynamic properties for these substances were computed for the ideal gaseous state using the rigid rotor harmonic oscillator approximation at 1 atm from 200° to 1000°K.