Synthesis and Structural Studies of Tetraaldehyde Phenylhydrazone and its Complex with Copper(II)

A binucleating ligand, incorporating four phenylhydrazone groups, 7,7′-methylene-bis(E,E)-3,11-dimethyl-5,9-dioxa-4,10-diaza-3,10-tridecadiene-2,12-dione]phenylhydrazone (4) (mtph) was synthesized, its dinuclear Cu(II) complex prepared and its metal complex characterized by elemental analyses, ¹H and ¹³C-n.m.r., i.r. and mass spectrometry. The elemental analysis, stoichiometry and spectroscopic data of the dinuclear Cu(II) complex indicate that the Cu(II) ions are coordinated to the ether oxygen and nitrogen atoms (C=N) of the tetrahydrazone, the with a 2:1 metal:ligand ratio. All spectral data support the proposed structure of mtph and its Cu(II) complex. In addion, the total energy and heat of formation (Figure 3) calculated for intramolecular hydrogen bonded and non-intramolecular hydrogen bonded tetrahydrazones (4, 5) by semiempirical AM1 calculations showed that tetrahydrazone (5) having intramolecular hydrogen bonds is more stable (ca. 10 kcal/mol) than the non-intramolecular hydrogen bonded form (4).