MICROWAVE-SPECTRUM, NUCLEAR-QUADRUPOLE COUPLING-CONSTANTS FOR CHLORINE, AND STRUCTURE OF 1-CHLORO-1-FLUOROALLENE

The microwave spectrum of 1-chloro-1-fluoroallene, ClFCCCH2, has been studied from the 8 to 40 GHz region, with a-type Q- and R-branch transitions in the ground vibrational state being assigned for 35Cl and 37Cl species. The rotational constants obtained are A = 6781.35(20) MHz, B = 2825.740(8) MHz, and C = 2019.404(10) MHz for 35Cl species, and A = 6701.41(37) MHz, B = 2770.447(15) MHz, and C = 1984.023(13) MHz for 37Cl species. The nuclear quadrupole coupling constants for 35Cl are determined to be χaa = -37.74 MHz, χbb = 1.18 MHz, and χcc = 36.56 MHz. The molecular structure which reproduces the observed moments of inertia has been determined. Both bond angles for halogen, ∠ClCC and ∠FCC, in 1-chloro-1-fluoroallene are found to be smaller than the corresponding angles in 1-chloro-1-fluoroethene. © 1990.