Microwave Spectrum, Barrier to Internal Rotation, Dipole Moment, and Structure of Trifluoromethylphosphine

Abstract
The microwave spectra of CF3PH2, CF3PHD, and CF3PD2 have been observed and analyzed. The barrier to internal rotation is 2360 ± 80 cal/mole, approximately 400 cal/mole higher than the barrier in CH3PH2. The dipole‐moment components are μ a = 1.77 ± 0.01 D , μ c = 0.74 ± 0.03 D , and μ total = 1.92 ± 0.02 D . The structural parameters are r C − P = 1.900 ± 0.006 Å, r P − H = 1.43 ± 0.08 Å, ∠ FCF = 108.0 ± 0.4°, ∠ CPH 91.9 ± 1.9° , and ∠ HPH = 96.7 ± 1.8° . Compared with CH3PH2, the C‐P bond is significantly longer, ∠CPH is smaller, and ∠HPH is larger.
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