# MICROWAVE SPECTRUM OF ETHYLPHOSPHINE-BORANE

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 Title: MICROWAVE SPECTRUM OF ETHYLPHOSPHINE-BORANE Creators: Durig, J. R.; Brletic, P. A.; Li, Y. S.; Johnston, S. A.; Odom, J. D. Issue Date: 1981 Abstract: The microwave spectra of $CH_{3}CH_{2}PH_{2} \ ^{11}BH_{3}, CH_{3}CH_{2}PH_{2} \ ^{10}BH_{3}$, and $CH_{3}CH_{2}PH_{2} \ ^{11}BD_{3}$ have been recorded in the region 18.0 to 39.0 GHz and those of $CH_{3}CH_{2}PH_{2} \ ^{11}BH_{3}$ and $CH_{3}CH_{2}PD_{2} \ ^{11}BD_{3}$ in the range 26.5 to 39.0 GHz. A-type transitions were observed and R-branch assignments have been made for all isotopes in the ground vibrational state. From the relative intensities of the microwave transitions, the Stark effect and the experimental rotational constants, it has been determined that the assigned spectra result from the trans conformer which is believed to be more stable than the gauche form at ambient temperature. The dipole moment components for trans-ethylphosphineborane were determined from the Stark effect to be: $|\mu_{a}| = 4.66\pm0.01 |\mu_{b}| = 1.34\pm0.03,and |\mu_{c}| = 4.85\pm0.02$D. With reasonable assumptions for the ethyl moiety, the following structural parameters for trans-ethylphosphineborane were calculated: r(B-P) = $1.917\pm 0.047 \AA r(B-H) = 1.197\pm 0.006 \AA, r(P-H) = 1.394\pm 0.007 \AA, \tau(P-C) = 1.809\pm 0.020 \AA. \ni BPC = 114.6\pm0.03^{\circ}, \ni PBH = 105.4\pm0.91^{\circ}, \ni CPH = 103.2\pm 0.03^{\circ}$, and $\ni PCC = 118.2\pm2.4^{\circ}$. These results will be compared to similar quantities in some analogous molecules. URI: http://hdl.handle.net/1811/11658 Other Identifiers: 1981-TB'-2