Structural characterisation of metal complexes containing 1-[(4-methylphenyl)sulfonamido]-2-[(2-pyridylmethylene)amino]benzene

Abstract

The interaction of 2-pyridinecarboxaldehyde with N-tosyl-1,2-diaminobenzene leads to the isolation of two different products, {3-[ethoxy(2-pyridyl)methyl]-1-[(4-methylphenyl)sulfonyl]-2-(2-pyridyl)-2,3-dihydro-1H-benzo[d]imidazole}, L¹, and {1-[(4-methylphenyl)sulfonyl]-2-(2-pyridyl)-2,3-dihydro-1H-benzo[d]imidazole}, L², but not to the expected Schiff base 1-[(4-methylphenyl)sulfonamido]-2-[(2-pyridylmethylene)amino]benzene, HL³. Two kinds of complexes, containing the potentially tridentate and monoanionic [L³]⁻ as a ligand, were obtained by different routes. ML³(p-Tos)(H₂O)_n complexes (p-TosH =  p-toluenesulfonic acid; M = Co, Cu, Zn; n  = 1–3) have been isolated by electrolysis of a solution phase composed of L¹ and p-toluenesulfonic acid, using metal plates as the anode. Metal complexes of composition ML³₂(H₂O)_n (M = Mn, Co, Cu, Zn; n  = 0–2) were obtained by template synthesis from M(acac)₂, 2-pyridinecarboxaldehyde and N-tosyl-1,2-diaminobenzene. All these compounds have been characterised by elemental analyses, magnetic measurements, IR, mass spectrometry and, in the case of M = Zn, by ¹H NMR spectroscopy. CuL³(p-Tos)(H₂O), 1, ZnL³(p-Tos)(H₂O), 2, CoL³₂, 3, CuL³₂, 4 and ZnL³₂·2CH₃CN, 5, were also crystallographically characterised.