Olav Steinnes, Quang Shen, Kolbjølrn Hagen
1980
Citations
0
Influential Citations
36
Citations
Journal
Journal of Molecular Structure
Abstract
Abstract Chloroacetyl chloride is studied by gas-phase electron diffraction at nozzle-tip tempera- tures of 18, 110 and 215°C. The molecules exist as a mixture of anti and gauche confor- mers with the anti form the more stable. The composition (mole fraction) of the vapor with uncertainties estimated at 2σ is found to be 0.770 (0.070), 0.673 (0.086) and 0.572 (0.086) at 18, 110 and 215°C, respectively. These values correspond to an energy difference with estimated standard deviation Δ E o = E o g - E o a = 1.3 ± 0.4 kcal mol −1 and an entropy difference ΔS o = S o g -S o a = 0.7 ± 1.1 cal mol −1 K −1 . Certain of the diffraction results permit the evaluation of an approximate torsional potential function of the form 2V = V 1 (1 - cos φ) + V 2 (1 - cos 2φ) + V 3 (1 - cos 3φ); the results are V 1 = 1.19 ± 0.33, V 2 = 0.56 ± 0.20 and V 3 = 0.94 ± 0.12, all in kcal mol −1 . The results for the distance ( r a ), angle ( ∠α ) and r.m.s. amplitude parameters obtained at the three temperatures are entirely consistent. At 18°C the more important parameters are, with estimated uncertainties of 2σ, r (C-H) = 1.062(0.030) A, r (CO) = 1.182(0.004) A, r (C-C) = 1.521(0.009) A. r (CO-Cl) = 1.772(0.016) A, r (CH 2 -Cl) = 1.782(0.018) A, ∠C-C-0 = 126.9(0.9)°, ∠CH 2 -CO-C1 = 110.0(0.7)°,∠CO-CH 2 -C1 = 112.9(1–7)°, ∠H-C-H = 109.5° (assumed), ∠φ (gauche torsion angle relative to 0° for the anti form) = 116.4(7.7)°, δ (r.m.s. amplitude of torsional vibration in the anti conformer) == 17.5(4.2)°.