LOW-FREQUENCY VIBRATIONAL SPECTRA AND RING-PUCKERING POTENTIAL ENERGY FUNCTION OF 2-PHOSPHOLENE AND 2-PHOSPHOLENE-1−d11-d_{1}

Author Institution: Department of Chemistry, Texas A\&M UniversityThe far-infrared and low-frequency Raman spectra of 2-phospholene, $CH=CHCH_{2}CH_{2}PH$, and 2-phospholene-$1-d_{1}$ have been recorded. Four infrared and three Raman ring-puckering transitions were observed for each isotopic species. Kinetic energy expansions, corresponding to reduced masses of 130.42 and 136.72 a.u., were calculated for the two species and these were used to determine the asymmetric potential function for ring-puckering for both molecules: $V(cm^{-1}) = 6.05 \times 10^{5} x^{4}+3.24 \times 10^{5} x^{3}+10^{4}x^{2}$, where x is the puckering coordinate in {\AA} units. The minimum at $x = 0$ corresponds to a puckered (presumably endo) conformation. Inflection points occur in the potential function at $x = -0.08 A$ (where $V = 205 cm^{-1}$) and $x = -0.19$ A (where $V = 524 cm^{-1}$). It is likely that the less-stable planar ring conformation and the less-stable puckered conformation (exo) may be associated with these values