Phenoxo bridged tetranuclear copper(II) and dinuclear zinc(II) complexes of 2,6-diformyl-4-methylphenol-di(benzoylhydrazone): Synthesis, structure, spectra and magnetism

• Cu(II)- and Zn(II)-2,6-diformyl-4-methylphenol-di(benzoylhydrazone) complexes.
• Cu(II) complex is tetranuclear Cu4[{(μ-OC6H2CH3)(2,6-CHN–NC(O)(C6H5)2)}2(μ-OCH3)2].
• Ligand and Zn complex are fluorescent active.
• Strong antiferromagnetic coupling with J = −186.5 cm−1 of Cu(II) complex.

Phenoxo bridged tetranuclear Cu(II) and dinuclear Zn(II) complexes are synhesized namely, Cu4[(L)2(OCH3)2] (1) and Zn2(HL)2 (2) (H3L = [(HOC6H2CH3){2,6-(CHN–NC(OH)(C6H5))(CHN–NC(OH)(C6H5))}]) and characterized by FTIR, UV–Vis, 1H NMR, fluorescence and mass spectrometry. Single crystal X-ray diffraction analysis of 1 shows that the Cu atom possesses a square pyramid environment via bridging of ‘phenolato’-O and ‘enolato’-O of the ligand, additional bridging of ‘methanolato’-O of coordinated CH3OH and monodentate coordination of imine-N. The EPR spectrum of 1 are characterized by g‖ = 2.286, A‖ = 169 × 10−4 cm−1, g⊥ = 2.068, A⊥ = 17 × 10−4 cm−1 (298 K) and g‖ = 2.283, A‖ = 178 × 10−4 cm−1, g⊥ = 2.072, A⊥ = 15 × 10−4 cm−1 (77 K). The study of the variable temperature magnetic properties agrees with a predominant intramolecular antiferromagnetic coupling (2J = −186.5 cm−1), rendering a ground state of S = 0.

Cu(II) and Zn(II) complexes, Cu4[{(μ-OC6H2CH3)(2,6-CHN–NC(O)(C6H5)2)}2(μ-OCH3)2] (1) and Zn2[(μ-OC6H2CH3){2,6-(CHN–NC(O)(C6H5))(CHN–NH–C(O)(C6H5))}]2 (2) have been synthesized in moderate yield. The Cu(II) atom adopts a square pyramidal geometry, to form a tetranuclear core. The magnetic behavior of the complex 1 shows predominant intramolecular antiferro-magnetic coupling. The ligand, 1 and complex 2 are emissive.Figure optionsDownload as PowerPoint slide