Activation of methane by zinc: gas-phase synthesis, structure, and bonding of HZnCH3. 
The methylzinc hydride molecule, HZnCH3, has been observed in the gas phase for the first time in the monomeric form using high-resolution spectroscopic techniques.  The molecule was synthesized by two methods: the reaction of dimethylzinc with hydrogen gas and methane in an AC discharge and the reaction of zinc vapor produced in a Broida-type oven with methane in a DC discharge.  HZnCH3 was identified on the basis of its pure rotational spectrum, which was recorded using millimeter/submillimeter direct-absorption and Fourier transform microwave techniques over the frequency ranges 332-516 GHz and 18-41 GHz, respectively.  Multiple rotational transitions were measured for this molecule in seven isotopic variants.  K-ladder structure was clearly present in all of the spectra, indicating a molecule with C3v symmetry and a (1)A1 ground electronic state.  Extensive quadrupole hyperfine structure arising from the (67)Zn nucleus was observed for the H(67)ZnCH3 species, suggesting covalent bonding to the zinc atom.  From the multiple isotopic substitutions, a precise structure for HZnCH3 has been determined.  The influence of the axial hydrogen atom slightly distorts the methyl group but stabilizes the Zn-C bond.  This study suggests that HZnCH3 can be formed through the oxidative addition of zinc to methane in the gas phase under certain conditions.  HZnCH3 is the first metal-methane insertion complex to be structurally characterized.