NMR INVESTIGATION OF ARYL- AND BENZYL-MERCURIC COMPOUNDS; EXPERIMENTAL EVIDENCE FOR ?-? CONJUGATION INVOLVING THE CARBON-MERCURY BOND

Article abstract of DOI:10.1016/S0022-328X(00)82466-3

199Hg and 13C NMR spectra of a large number of aryl- and benzyl-mercuric compounds (ArHgX and ArCH2HgX) have been obtained, in order to throw more light on the relationship between the coordination state of the mercury atom and its NMR parameters.For the aryl series ArHgCl there is a good correlation between the 199Hg chemical shift and ?⁺, with electron releasing substituents in Ar resulting in an upfield chemical shift.This correlation arises from the contribution of the paramagnetic term to the chemical shift.Comparison of the NMR parameters in ArHgCl and ArCH2HgCl provides unambiguous evidence for conjugation between the C-Hg bond in ArCH2HgCl and the aromatic ring, the C-Hg system behaving as a strongly donating group.This is explained in terms of vertical stabilization, as proposed by Traylor.