Synthesis, Spectroscopic Characterization, and X-ray Structure of the Co-crystal Copper(II) Complex of the Dissymmetrical 1-(2 hydroxy-3-methoxybenzylidene)-5-(pyridin-2 ylmethylene) Carbnohydrazide Ligand

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In the pentanuclear title complex, bis{<i>μ</i>₂-1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide}-1<i>κ</i>⁴<I>O</I>,<I>N</I>,<I>N</I>’,<I>N</I>’’:2<i>κ</i>²<I>O</I>,<I>N</I>;2<i>κ</i>²<I>O</I>,<I>N</I>:3<i>κ</i>⁴<I>O</I>,<I>N</I>,<I>N</I>’,<I>N</I>’’-1,2,3-tricopper(II) bis{[1-(2-oxido-3-methoxybenzylidene)-5-(pyridin-2-ylmethylene)carbonohydrazide]-<i>κ</i>⁴<I>O</I>,<I>N</I>,<I>N</I>’,<I>N</I>’’-copper(II)} tetraperchlorate tetrahydrate (1), two monocationic mononuclear units and one dianionic trinuclear unit co-exist. The Cu<SUP>II</SUP> centers in the mononuclear units as well as the two terminal Cu<SUP>II</SUP> centers in the trinuclear unit are located in the N₃O cavity of the ligand and are coordinated to a phenolate oxygen atom, to a pyridine nitrogen atom, to an imino nitrogen atom and to a hydrazinyl nitrogen atom. The third central Cu(II) atom in the trinuclear unit, which is hexacoordinated, is located in N₂O₄. The metal center is coordinated to two ligand molecule through one imino nitrogen atom one oxygen atom of a carbonyl moiety per ligand and two oxygen atom of water molecules. The tetracoordinated copper(II) ions are situated in distorted square planar environments, while the hexacoordinated copper(II) is located in octahedral geometry. In the mononuclear units, as well as in the trinuclear units, the methoxy oxygen atoms remain uncoordinated. Each atom of the uncoordinated perchlorate anions is disordered over two sets of sites in a 0.5 ratio. Four free water molecules are also present. In the crystal, the trinuclear cationic unit and the mononuclear cationic units are assembled into infinite layers. These layers are held together via electrostatic interactions, forming a three-dimensional structure.