The Molecular Structure of Ethyl Chloride as Determined by a Combined Use of the Electron-diffraction Data and the Spectroscopic Moments of Inertia

Abstract

Abstract The molecular structure of ethyl chloride has been determined by a joint analysis of the electron-diffraction data and the moments of inertia obtained by Schwendeman and Jacobs by means of microwave spectroscopy. In the analysis, a staggered conformation with Cs symmetry for the molecule and a local C3v symmetry about the C–C axis for the methyl group were assumed. Under the further assumptions that \varphiav(HCH)CH2 is 109.2±2° and \varphiav(CCH)CH2 is in the range of 113.6–109.6°, the following parameter values were determined: rg(C–C) 1.528(4) Å; rg(C–Cl), 1.802(3) Å; rg(C–CI), 2.746(5) Å; rg; rg(C–H)CH2, 1.103(4) Å; \varphiav(HCH)CH2, 110.0(1.6)°; and \varphiav(CCCl), 110.7(0.3) °. The rg and rs distances for the C–Cl and C-C bonds of various chlorinated alkanes were plotted against the difference between the numbers of methyl groups and chlorine atoms, Δn=n(CH3)–n(Cl). In general, as the number of chlorine atoms increases, both distances become shorter, though the rg distances are longer than the rs distances by 0.01–0.03 Å.