Structure and properties of the dinuclear complex [Co2(μ-OAc)2(OAc)2(μ-H2O)(phen)2]

The dinuclear complex [Co2(μ-OAc)2(OAc)2(μ-H2O)(phen)2] has been prepared and its structure was determined. The compound crystallizes in the monoclinic space group P2(1)/c. The Co–Co distance is 3.574 Å and is similar to the Fe–Fe distance in the reduced methane monooxygenase hydroxylase. The electronic and IR spectra of the complex confirm octahedral coordination of the cobalt atoms and formation of strong O–H⋯O hydrogen bonds in the solid state. The dependence of the magnetic susceptibility of the complex on temperature indicates an antiferromagnetic interaction, the value of the isotropic exchange parameter J was estimated to be −2.1 cm−1. The 1H NMR spectra show that in organic solvents the structure of compound is the same as in the solid state, however, in water solution the complex dissociates giving compounds with different Co:phen ratios.

The dinuclear complex [Co2(μ-OAc)2(OAc)2(μ-H2O)(phen)2] has a structure analogous to that of metalloenzymes, Co(II) atoms are bridged by two acetato and an aqua ligand. The complex exhibits antiferromagnetic exchange, TN = 4.5 K, with an isotropic exchange parameter J = −2.1 cm−1. The crystal structure of compound 1 is stabilized by O–H⋯O hydrogen bonds and stacking of 1,10-phenanthroline ligands. The proton NMR spectrum indicates that the structure of the complex in CD2Cl2 solution is the same as in the solid state.Figure optionsDownload as PowerPoint slide