Microwave Spectrum of Ethyl Chloride

Abstract

The microwave spectrum of ethyl chloride has been investigated and accurate values for the rotational constants B and C for several isotopic species have been obtained. For C₂H₅Cl³⁵, B=5493.8 Mc, C=4962.3 Mc, and for C₂H₅Cl³⁷, B=5379.1 Mc and C=4867.1 Mc. Two deuterated species have been studied. For trans CH₂DCH₂Cl³⁵, B=5098.8 Mc and C=4637.5 Mc. The rotational constants for gauche CH₂DCH₂Cl³⁵ are B=5297.6 Mc and C=4784.9 Mc. The following model reproduces these constants to within 4 Mc: d C–C=1.5495 A, d C–H=1.101 A, d C–D=1.090 A, ≰ HCH=110° 00′, ≰ CCCl=110° 30′, d C–Cl=1.7785 A. From the structural data obtained for the deuterated ethyl chlorides it has been possible to establish the staggered configuration as the equilibrium configuration. The quadrupole analysis shows that eqQ along the C–Cl bond axis is —70.07 Mc for Cl³⁵ and —55.03 Mc, for Cl³⁷, indicating an ionicity of 25%. The torsional frequency has been estimated to be 236 cm^—1 and the barrier height is 3.4 kcal/mole.