Microwave spectrum, dipole moment, barrier to internal rotation of 1,1-dimethyldiborane
Abstract
The microwave spectra of four isotopic species of 1,1-dimethyldiborane have been investigated in the region between 18.0 and 40.0 GHz. The observed rotational constants (MHz) for the normal species are A=7070.68(7), B=6606.57(3), C=3660.33(1); for 10B1 species, A=7069.87(15), B=6605.79(5), C=3659.88(3); and for 10B2 species, A=7070.63(27), B=6889.89(10), C=3745.92(6). The B-B distance determined by the Kraitchman method is 1.76(2) Å. The carbon-boron structure could be fitted to the moments of inertia by assuming reasonable values for the other structural parameters: r(B1-C)=1.59 Å and <CBC=121.2°. From the Stark effect measurements, the dipole moment is measured to be 0.87(3) D. Assuming no coupling between the rotors, the barrier height to internal rotation is 1.39(16) kcal/mol.
- Publication:
-
Journal of Chemical Physics
- Pub Date:
- March 1983
- DOI:
- 10.1063/1.445182
- Bibcode:
- 1983JChPh..78.3562C