3-Butenenitrile (allylcyanide): Molecular structure and conformation in the gas phase as determined by electron diffraction

Abstract

A gas phase electron diffraction study of 3-butenenitrile shows that at 20°C there is 94 ± 18% syn conformer (CCN bond eclipsing the double bond, τ = 0°). The syn structure results in terms of r a distance and ∠ α angles are as follows: r( C C = 1.326(7) A ̊ , r(= C C) = 1.508(5) A ̊ , r(= C C) – r( C CN) = 0.048(8) A ̊ , r( C N) = 1.162(7) A ̊ , r(= C H) = 1.085(8) A ̊ , r(– C H) – r(= C H) = 0.012(1) A ̊ , ∠ C= C C = 125.5(1.8)°, ∠ C C C = 114.0(1.0)°, 〈∠ C= C H〉 = 120.8(3.0)° (〈〉 denoting average), 〈∠ C C H〉 = 111.4(1.2)°, 〈τ S 2〉 1 2 ( syn root mean square torsional amplitude) = 13.8(5.3)°. Uncertainties are given as 2σ, where σ includes uncertainty due to correlation among observations, electron wavelength and other parameters used in the data reduction. A study at 180°C leads to conclusions consistent with the 20°C data.