MICROWAVE-SPECTRUM OF CHLOROBORANE, BH2CL

The microwave spectrum of BH2Cl existing as an intermediate in the reaction between diborane and boron trichloride was observed. The lifetime of this molecule in a brass waveguide cell was found to be less than 1 s. The observed spectrum indicated the molecule to be planar with C2v symmetry. The rotational constants were determined for (BH2Cl)-B-11-Cl-35, (BH2Cl)-B-11-Cl-37, (BH2Cl)-B-10-Cl-35, and (BD2Cl)-B-11-Cl-35, and were employed to calculate the structure parameters (r(s)):r(B-H) = 1.1916(2) angstrom, r(B-Cl) = 1.7353(5) angstrom, and angle HBH = 124.22(3)-degrees. The quadrupole coupling constants of Cl, an extraordinarily small chi(zz) and a large eta compared to related molecules, were obtained. The dipole moment was determined to be mu(a) = 0.75 (5) D for BH2Cl.