Microwave Spectrum, Structure, Dipole Moment, and Barrier to Internal Rotation of Phosphorus Trifluoride—Borane

• Published in: The Journal of chemical physics 1967-01, Vol.46 (1), p.357-365
• Main Authors: Kuczkowski, R. L., Lide, David R.
• Format: Article
• Language: English
• ISSN: 0021-9606; 1089-7690
• DOI: 10.1063/1.1840394

The microwave spectrum of several isotopic species of phosphorus trifluoride—borane (F3PBH3) has been measured and the following structural parameters determined: d(BH) = 1.207±0.006 Å; d(PF) = 1.538±0.008 Å; d(PB) = 1.836±0.012 Å; ∠HBH=115°04′±1°; ∠FPF=99°50′±1°. The dipole moment was evaluated from Stark splittings as 1.64±0.02 D. The vibrational satellite spectrum associated with the excited ν12(E) and ν6(A2) states for F3P11BH3 was found to be strongly perturbed and was fitted to the theory for a first-order Coriolis interaction. The analysis of this perturbation and the measurement of the ν12 fundamental in the infrared spectrum permitted the inactive torsional fundamental ν6 to be determined as 197±5 cm−1. This leads to a potential barrier to internal rotation of 3240±150 cal/mole. The enthalpy of dissociation for the reaction 2 F3PBH3⇆2 PF3+B2H6 (298°) was determined as 10.99 kcal. The experimental results are compared to those found for other related compounds.