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

The new molecular nickel(II) complex, namely, {4-bromo-2-[({N'-[(2-oxidobenzylidene)aminolcarbamimidoyllimino)methyl]phenolatolnickel(II) N,N-dimethyl-formamide solvate monohydrate, [Ni(Ci(15)H(11)BrN(4)O(2))]-C3H7NO center dot H2O, (I), crystallizes in the triclinic space group P (1) over bar 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 angstrom, cis angles in the range 83.08 (5)-95.35 (5)degrees, trans angles of 177.80 (5) and 178.29 (5)degrees] The complex molecule adopts an almost planar conformation. In the crystal, a complicated hydrogen-bonded network is formed through N-H center dot center dot center dot N/O and O-H center dot center dot center dot O intermolecular interactions. Complex (I) was also characterized by FT-IR and H-1 NMR spectroscopy. It undergoes an Ni-II <-> H Ni-III redox reaction at E-1(/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 similar to 178 mV.

Automated summary

The new molecular nickel(II) complex features a unique chelating ligand structure and shows promising photoelectric properties.