Rotational spectrum and angular geometry of a pre-reactive complex of oxirane and F2

Rotational spectra of two isotopomers, (CH2)2O … F2 and (CD2)2O … F2, of a pre-reactive complex of oxirane and F2 were observed with a Balle-Flygare microwave spectrometer. Chemical reaction between the components was avoided by use of a fast-mixing nozzle. Rotational (A0, B0, C0) and centrifugal distortion (ΔJ, ΔJK, δK) constants were determined for each isotopomer. The complex has an angular geometry isomorphous with those of oxirane … HCl and oxirane … ClF, with φ = 98(6)°, the O … FF noncollinear by at most 10° and r(O … F) = 2.69(6) Å. A comparison of oxirane … F2 and oxirane … Ar reveals similarities understandable in terms of the F2 electric charge distribution.