MOLECULAR-STRUCTURE AND INTERNAL-ROTATION OF (Z)-(PROPIONALDEHYDE OXIME) BY GAS-PHASE ELECTRON-DIFFRACTION AND MICROWAVE SPECTROSCOPY

The molecular structure of gaseous (Z)-(propionaldehyde oxime) has been determined by the joint analysis of electron diffraction data and rotational constants. The molecular structure optimization has also been performed by molecular orbital calculations. The molecular skeleton is planar, but the internal rotation around the C-C(= N) bond is a large amplitude motion with a potential barrier height of V1 = 1.5 kcal mol-1. The geometrical molecular parameters obtained are: r(g)(C(m)-C) = 1.549 +/- 0.003 angstrom, r(g)(C-C) = 1.497 +/- 0.002 angstrom, r(g)(C = N) = 1.295 +/- 0.001 angstrom, r(g)(N-0) = 1.430 +/- 0.002 angstrom, angle CCC = 109.4 +/- 0.40, angle CCN = 127.5 +/- 0.3-degrees and angle CNO = 109.3 +/- 0.3-degrees.