Vinylmercury Hydrides:  Synthesis and Spectroscopic Characterization

The first vinylmercury hydrides, and among them the parent compound, have been prepared by a chemoselective reduction of the corresponding vinylmercury chlorides with tributylstannane in the presence of a radical inhibitor. These hydrides have been characterized on the basis of their spectral data (1H, 13C, and 199Hg NMR spectroscopy and mass spectrometry). The photoelectron spectra of the ethenylmercury hydride displays bands at 9.79, 10.13, 11.41, and 13.20 eV. On the basis of photoelectron spectra and ab initio quantum chemical calculations some (d−p)π interaction between the vinyl π-system and the mercury d-orbitals could be concluded. Vinylmercury hydrides have been condensed and then revaporized in vacuum at low temperature, but they exhibit a very low stability at room temperature even diluted in toluene (τ1/2 ≈ 1 min); elemental mercury and the corresponding divinylmercury were formed under these conditions.