The direct electrochemical synthesis of d10 metal ion derivatives of some anionic bidentate oxygen donors

Abstract

The electrochemical oxidation of a sacrificial anode (M = Zn, Cd, Hg, In, Sn) in non-aqueous solutions of 3-hydroxyflavone, 1′-hydroxy-2′-acetonaphthone, or 2-ethoxyphenol (= HL) gives ZnL2, CdL2, HgL, InL3, or SnL2 (not all combinations). Adducts with 2,2′-bipyridine (bpy) or N,N,N′,N′-tetramethylethanediamine (tmen) have also been prepared in some cases. Certain zinc and cadmium compounds produce paramagnetic species on exposure to the atmosphere. The structure of Zn(C15H9O3)2tmen has been determined; the crystals are orthorhombic, space group Pbcn, cell dimensions a = 18.817(2) Å, b = 13.886(3) Å, c = 12.567(3) Å, Z = 4, R = 0.0758 for 773 unique observed reflections. The corresponding data for Cd(C12H9O2)2bpy are orthorhombic, space group Pbca, cell dimensions a = 20.338(4) Å, b = 30.473(5) Å, c = 9.316(2) Å, Z = 8, R = 0.0457 for 2623 unique observed reflections. Both molecules have MO4N2 kernels, but each shows significant differences in the two M—O bond lengths to the dioxo ligand, and there are concomitant effects in the C—O and C—C bond distances in the ligands. Keywords: electrochemical synthesis, d10 metal ions, X-ray crystallography, zinc complex, cadmium complex.