Synthesis, characterization and X-ray crystal structure of an allyloxo functionalized nonsymmetric nickel coordination complex based on N₂O₂ chelating ferrocenyl ligand

The synthesis of the new air and thermally stable orange neutral dinuclear iron-nickel unsymmetrical Schiff base complex, [8-(2-oxo,5-allyloxo-phenyl)-4,7-diaza-3-methyl-1-ferrocenyl-1-one-octa-1,3,7-trienato]nickel(II) (2), was achieved via the Williamson coupling reaction between the 2-oxo,5-hydroxyphenyl precursor 1 and allyl chloride in the presence of base. Complex 2 was isolated in 68% yield and characterized by IR, UV-Vis, ¹H and ¹³C NMR spectroscopy, HRMS and authenticated by a single crystal X-ray diffraction analysis. The organometallic/inorganic hybrid complex 2 consists in a ferrocenyl fragment linked to a classical Werner-type complex made of an unsymmetrical quadridentate N₂O₂ Schiff base ligand with a pendant allyl ether functionality as a potential anchoring group. The Ni(II) center displays a square-planar geometry with the nitrogen and oxygen atoms occupying mutually trans positions. The structure of 2 · H₂O shows that the water crystallization molecule interacts through two distinct intermolecular hydrogen bonds with the two oxygen atoms of the tetradentate N₂O₂ acyclic chelating ligand, forming in the solid state, a distorted six-membered ring.