COMPLEXATION OF 7-AZAINDOLE BY THE METHYLMERCURY(II) CATION

Complexes of the types [CH3Hg(aza)], [CH3Hg(Haza)]X, and [(CH3Hg)2(aza)]X are obtained by reacting CH3HgOH and/or CH3HgX (X = NO3, ClO4) with 7-azaindole (Haza). The weakly acidic N 1 -H proton on the pyrrole ring is displaced by the hydroxide, whereas the perchlorate and nitrate salts lead to CH3Hg+ coordination to the N7 lone pair on the pyridine ring. Detailed analysis of the infrared spectra of the complexes and their N-deuterated derivatives provides diagnostic regions for eventual prediction of the coordination mode in other systems. All compounds are characterized by means of H-1, C-13, and Hg-199 NMR spectra in DMSO solution and solid-state CP-MAS C-13 Spectra. Comparison of the solution and solid-state C-13 spectra show that the species present in the solids remain undissociated in DMSO. Each type of complex can be identified from a characteristic pattern of large displacements of the ligand C-13 signals. The H-1 spectra are less informative because substitution of the N1-H proton by CH3Hg+ induces only minor shifts. Metal solvation appears to have a major influence on the C-13 and Hg-199 chemical shifts of the CH3Hg+ groups.