M. A. FLORY, A. J. APPONI AND L. M. ZIURYS, Department of Chemistry, Department of Astronomy, Steward Observatory, University of Arizona, Tucson, AZ 85721.
The pure rotational spectrum of HZnCH3 has been observed in its ground electronic state (X 1A1) using both direct absorption and Fourier transform microwave techniques in the frequency range 18-516 GHz. Twelve rotational transitions of this symmetric top species were recorded in K-ladders up to K = 7. The molecule was synthesized from Zn(CH3)2 in an AC discharge and also from Zn (vapor) + CH4 with a DC discharge. From measurements of the spectra of various isotopic species (66Zn, 67Zn, 68Zn, 13C, and 2H), an accurate structure has been determined. The H-C-H bond angle was found to be 108.7\circ, slightly smaller than that in ZnCH3 or CH4. In addition, nuclear spin-rotation (I . J) interactions with the methyl hydrogen nuclei and electric quadrupole coupling from the 67Zn nucleus were resolved in the FTMW spectrum. From these data, hyperfine parameters have been established. The value of eqQ = -109.125(11) MHz indicates that the bonds to zinc are primarily covalent. Detection of this species, especially via the Zn + CH4 pathway, is a good indication of the ability of metal atoms to insert into C-H bonds.