Oximato bridged dinuclear copper(II) complexes: Synthesis, crystal structure, magnetic, thermal, electrochemical aspects and BVS analysis

Reactions of the Schiff-base ligand, 2-hydroxyimino-3-(2-hydrazonopyridyl)-butane (LH) with copper(II) perchlorate hexahydrate and copper(II) nitrate trihydrate in 1:1 molar proportion in methanol give rise respectively to Cu2L2(ClO4)2 (1a) and Cu2L2(NO3)2 (1b) in substantial yields. The complexes have been characterized by C, H and N microanalyses, copper estimation, ESI-MS, FT-IR, UV–Vis spectra, molar electric conductivity and room temperature magnetic susceptibility measurements. The X-ray crystal structures of both 1a and 1b have been determined. The structures reveal that both the complexes are oximato bridged dinuclear Cu(II) assemblies. The electrochemical studies of 1a and 1b show Cu(II) to Cu(III) oxidation in methanol. The thermal behavior of the nitrate analog, 1b, has also been forwarded to delve into the structure. Bond-Valence Sum (BVS) method of analyses was also performed to assign the oxidation state for each copper center both in 1a and 1b.

Two dinuclear copper(II) compounds Cu2L2(ClO4)2 (1a) and Cu2L2(NO3)2 (1b) with LH = 2-hydroxyimino-3-(2-hydrazonopyridyl)-butane have been synthesized and characterized. These oximato bridged copper complexes are in ‘N3O2’ coordination chromophore. Each copper center is in square pyramidal coordination environment. The compounds are antiferromagnetically spin-coupled. The electrochemical studies show Cu(II) to Cu(III) oxidation in methanol in a sequential two-step monoelectronic pathway. Semi-empirical Bond-Valence Sum (BVS) method of analyses were also undertaken to assign the oxidation state of each copper center both in 1a and 1b.Figure optionsDownload as PowerPoint slideHighlights
► Schiff-base ligand.
► Syntheses of oximato bridged binuclear Cu(II) complexes.
► X-ray crystal structures.
► Redox studies.
► BVS calculation.