Carbon-13 and Proton Nuclear Magnetic Resonance Spectra of Methylmercury Nitrate in Strong Acids

Abstract

Abstract Proton and carbon-13 nuclear magnetic resonance spectra and Raman spectra of some methylmercury compounds, CH3HgX, were measured. The spin-spin coupling constants, 2J(199Hg–H) and 1J(13C–H) of methylmercury nitrate in some strong acids were found to increase when the proton resonance of the methyl group attached to the mercury shifts to lower magnetic field. It was also found that the C–H stretching bands of the methyl group shift to higher frequency in the strong acids. The results are explained by an increase of the effective positive charge on the mercury. As has been observed in other alkylmercury compounds, the spin-spin coupling constant between directly bonded mercury and carbon nuclei, 1J(199Hg–C),of some methylmercury compounds in organic solvents increased with the geminal spin-spin coupling constant, 2J(199Hg–H). The 1J(199Hg–13C) value of methylmercury nitrate in strong acids was found to decrease, whereas the 2J(199Hg–H) values increased in these media. The lowering of the mercury-carbon bond strengths in the strong acids, which was revealed from the mercury-carbon stretching frequency in the Raman spectra, is considered one possible reason for the decrease of the 1J(199Hg–13C) value.