Microwave spectrum, Structure, Dipole Moment and Nuclear Quadrupole Effects in Vinyl Chloride.

The microwave spectra of nine isotopic species of vinyl chloride have been measured and analysed, yielding moments of inertia from which a molecular structure was calculated. The bond lengths found are in A CC 1.332, C-Cl 1.726, average C-H 1.08. The bond angles are C2C1Cl 122, C2C1H1 124, C1C2H3 cis to Cl 121, C1C2H2 trans to Cl 120. Planarity was assumed. The chlorine nuclear quadrupole hyperfine lines were re-examined. From the data for several isotopic species it was shown that the C-C1 bond direction is within five degrees of a principal axis of the field gradient tensor. The lack of cylindrical symmetry of the field gradient about the C-C1 bond was confirmed. This is evidence that the observed shortening of the C-C1 bond is at least in part due to conjugation with the CC double bond and not solely to hybridization effects. The component of dipole moment along the a inertial axis was found to be 1.42 0.02 D. Author