NiII mol­ecular complex with a tetra­dentate amino­guanidine-derived Schiff base ligand: structural, spectroscopic and electrochemical studies and photoelectric response

The new mol­ecular nickel(II) complex, namely, {4-bromo-2-[({N′-[(2-oxidobenzylidene)amino]carbamimidoyl}imino)methyl]phenolato}nickel(II) N,N-di­methyl­formamide solvate monohydrate, [Ni(C15H11BrN4O2)]·C3H7NO·H2O, (I), crystallizes in the triclinic space group PUnlabelled Image with one mol­ecule per asymmetric unit. The guanidine ligand is a product of Schiff base condensation between amino­guanidine, salicyl­aldehyde and 5-bromo­salicyl­aldehyde templated by Ni2+ ions. The chelating ligand mol­ecule is deprotonated at the phenol O atoms and coordinates the metal centre through the two azomethine N and two phenolate O atoms in a cis-NiN2O2 square-planar configuration [average(Ni—N/O) = 1.8489 Å, cis angles in the range 83.08 (5)–95.35 (5)°, trans angles of 177.80 (5) and 178.29 (5)°]. The complex mol­ecule adopts an almost planar conformation. In the crystal, a complicated hydrogen-bonded network is formed through N—H⋯N/O and O—H⋯O inter­molecular inter­actions. Complex (I) was also characterized by FT–IR and 1H NMR spectroscopy. It undergoes an NiII ↔ NiIII redox reaction at E1/2 = +0.295 V (vs Ag/AgCl) in methanol solution. In a thin film with a free surface, complex (I) shows a fast photoelectric response upon exposure to visible light with a maximum photovoltage of ∼178 mV.