Mixed valent/geometry, linear, tetranuclear nickel complex bearing ONO pincer ligand exhibiting hitherto unknown ligation mode

A hitherto unknown linear, tetranuclear nickel(II/III) complex possessing both square-planar and pentagonal bipyramidal geometry around the metal ions was obtained from the reaction of ONO pincer ligand (E)-N'-(2-hydroxybenzylidene)acetohydrazide with [NiCl2(PPh3)(2)] precursor complex in methanol medium. The novel ONO ligand and its nickel complex were characterized by analytical and spectral data. The identity of the tetranuclear complex crystallized in triclinic crystal system with Pi space group was confirmed by single-crystal XRD study. Density Functional Theory (DFT) calculations performed for the optimization of the titled nickel complex by considering the presence as well as the absence of coordinated solvent molecules in the input coordinates revealed that the optimized structures are energetically somewhat disfavored but its formation in the experiment could be attributed to the participation of packing forces that stabilizes the molecule it in the solid state. (C) 2017 Elsevier Ltd. All rights reserved.