Conformational stability, r0 structural parameters, vibrational assignments and ab initio calculations of ethyldichlorophosphine

• Vibrational data indicate the presence of two conformers.
• The enthalpy difference going from the trans form to the gauche form is 88 ± 9 cm−1.
• Estimated r0 structural parameters have been determined for both conformers.
• Ab initio calculations have been performed for both forms.

Variable temperature (−60 to −100 °C) studies of ethyldichlorophosphine, CH3CH2PCl2, of the infrared spectra (4000–400 cm−1) dissolved in liquid xenon have been carried out. From these data, the two conformers have been identified and the enthalpy difference has been determined between the more stable trans conformer and the less stable gauche form to be 88 ± 9 cm−1 (1.04 ± 0.11 kJ/mol). The percentage of abundance of the gauche conformer is estimated to be 57% at ambient temperature. The conformational stabilities have been predicted from ab initio calculations by utilizing many different basis sets up to aug-cc-pVTZ for both MP2(full) and density functional theory calculations by the B3LYP method. Vibrational assignments have been provided for both conformers which have been predicted by MP2(full)/6-31G(d) ab initio calculations to predict harmonic force fields, wavenumbers of the fundamentals, infrared intensities, Raman activities and depolarization ratios for both conformers. Estimated r0 structural parameters have been obtained from adjusted MP2(full)/6-311 + G(d,p) calculations. The results are discussed and compared to the corresponding properties of some related molecules.

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