Synthesis and characterization of Zn(II), Cd(II) and Hg(II) complexes with imidazole derivatives. Crystal structure of dichloro-bis (5-amino-4-carboethoxy-1-p-methoxyphenylimidazole)zinc(II)

Article abstract of DOI:10.1016/S0020-1693(96)05509-0

Two imidazole-derivative ligands, 5-amino-4-carboethoxy-1-p-methoxyphenyl-imidazole (L) and 5-amino-4-nitrile-1-p-methoxyphenylimidazole (L′), have been prepared and their interactions with Zn(II), Cd(II) and Hg(II) reported. For the L ligand a series of complexes of general formulae MC₂L_x, where x = 1 or 2, has been obtained while for the L′ ligand only the Cd(II) complex fits with the general formulae. For this latter ligand the corresponding Hg(II) complexes were not isolated and a Zn(II) complex was obtained with the ligand in the protonated form. All the complexes have been characterized by spectroscopic and thermal techniques. In addition, the crystal structure of the ZnCl₂L₂ complex is reported. The compound crystallized in the monoclinic system, space group P-1, with cell constants a = 8.7328(18), b = 10.5494(21) and c = 17.3269(34) A, α = 75.265(10), β = 81.094(17) and γ = 70.939(11)° and Z=2. The structure was solved and refined to R = 0.056 (R_w = 0.031). The structure consists of discrete neutral ZnCl₂L₂ entities in which the L ligand coordinates through the N atom belonging to the imidazole ring, the Zn(II) ion exhibiting a distorted tetrahedral geometry.