Infrared and Raman spectra, structural parameters, conformational stability, vibrational assignment and ab initio calculations of 2-cyanoethylphosphine

Abstract

Infrared (3200–400cm−1) and Raman spectra (3050–50cm−1) of 2-cyanoethylphosphine, NCCH2CH2PH2, were recorded. Rotation about C–C bond gives Trans (T) and Gauche (G) conformers and rotation around C–P bond gives trans (t) and gauche (g) forms. Enthalpy differences in xenon solution by variable temperature Raman spectra between Gt and Tt gives 89±12cm−1 and Tg 331±18cm−1. Ab initio calculations by MP2(full) and DFT calculations were carried out. From previously reported microwave rotational constants and MP2(full)/6-311+G(d,p) predicted structural values, adjusted r0 parameters were obtained for three conformers. The determined heavy atom parameters for Gt [Tt] {Tg}: distances (Å) P1–C2=1.860(3) [1.858(3)] {1.864(3)}, C2–C3=1.534(3) [1.535(3)] {1.535(3)}, C3–C4=1.464(3) [1.465(3)] {1.463(3)}, C4–N5=1.160(3) [1.160(3)] {1.160(3)} angles (°) ∠P1C2C3=117.1(5) [114.9(5)] {110.0(5)}, ∠C2C3C4=112.5(5) [112.1(5)] {111.8(5)}, τP1C2C3C4=63.4(5) [180.0(5)] {176.8(5)}. Vibrational assignments are reported, supported by ab initio predictions.