MICROWAVE SPECTRUM AND STRUCTURE OF BICYCLO[1.1.0]BUTANE

The microwave spectra of four isotopic species of bicyclo[1.1.0] butane have been investigated and the rotational constants of each species have been determined. Combining these data with those of the previously studied normal isotopic species, a complete set of structural parameters have been found. These include C1-C3= 1.497 Å, C2-C 4= 1.498 Å, C2-C3= 1.071 Å C-H (methylene) = 1.093 Å, ∠C1C3H6= 128°22′, dihedral angle, α, between cyclopropane rings =121°40′, ∠HCH=115°34′. These results are discussed with regard to the electronic structure of the molecule.