THE MICROWAVE SPECTRUM AND STRUCTURE OF THE $(CH_{3}l_{2}NH - SO_{2}$ COMPLEX

Author Institution: Department of Chemistry, University of MichiganThe microwave spectra of $(CH_{3})_{2}NH SO_{2}$ have been observed with a pulsed beam. Fourier transform microwave spectrometer. In addition to the normal isotopic form, we have observed the spectra of $[CH_{3})_{2}NH {^{34}}SO_{2}. [CH_{3})_{2}ND- SO_{2}. (CH_{3})_{2}NH -SO_{18}O(H). (CH_{3})_{2}NH - SO_{18}O(C)$, and $(CH_{3})_{2}{^{15}}NH - SO_{2}$. The transitions are characterized by both a- and c-type selection rules. The rotational constants (in MHz) for $(CH_{3})_{2}NH - SO_{2}$ are $A = 4445.495(3), B = 2063.031(1)$ and $C = 1752.470(1)$. Stark effect measurements give electric dipole components of $mu_{a} = 4.030(4)$ and $\mu_{c} = 1.752(4)$ Debye. The structure of this complex, based on the isotopic substitution data, has no symmetry plane even though $\mu_{b}$ is 0 within experimental uncertainty. The N-S distance (2.35 A) is a little longer than for the trimethylamine. $SO_{2}$ complex (2.27 A) and reflects the strength of the complex $(\Delta H_{diss} = 10 kcal/mole)$. There is no evidence for any internal motion in this complex