A tetracopper(II) complex with N,N′-bis(picolinoyl)hydrazine

Synthesis, physical properties and X-ray structure of a hydrated tetranuclear copper(II) complex [Cu4(μ-diph)2(μ-H2O)2(O2CCH3)4(H2O)2]·4H2O with N,N′-bis(picolinoyl)hydrazine (H2diph) are reported. The centrosymmetric complex has two types of copper(II) centres with distorted square-pyramidal N2O3 coordination spheres. The dinucleating trans planar diph2− ligands are parallel to each other and act as N2O-donor to one metal centre and N2-donor to the other metal centre. The complex has a rectangular {Cu4(μ-N–N)2(μ-OH2)2} core with Cu···Cu distances as 4.834(1) and 3.762(1) Å. Solid state as well as solution electronic spectra show several transitions in the wavelength range 700–280 nm. The room temperature (298 K) solid state magnetic moment is 3.55 μB. The powder EPR spectra at 298 and 130 K are very similar and axial (g∥ = 2.25 and g⊥ = 2.08) in character.

Synthesis, characterization, physical properties and X-ray structure of [Cu4(μ-diph)2(μ-H2O)2(O2CCH3)4(H2O)2]·4H2O (H2diph = N,N′-bis(picolinoyl)hydrazine) have been described. The complex has a rectangular {Cu4(μ-N–N)2(μ-OH2)2} core with 4.834(1) and 3.762(1) Å Cu···Cu distances.Figure optionsDownload as PowerPoint slideResearch highlights
► Reaction of N,N′-bis(picolinoyl)hydrazine (H2diph) and Cu(O2CCH3)2·H2O in 1:2 mole ratio in methanol provided [Cu4(μ-diph)2(μ-H2O)2(O2CCH3)4(H2O)2]·4H2O.
► It was characterized by various spectroscopic and X-ray crystallographic measurements.
► Each diph2− in this centrosymmetric complex acts as N2O-donor to one Cu and N2-donor to the other Cu.
► No spin-exchange of note between the metal centres in the {Cu4(μ-N–N)2(μ-OH2)2} core.