First principles studies of the electronic and magnetic structures of [Fe(pz)2]x complex

Polybis(pyrazolato)iron(II), [Fe(pz)2]x is characterized by doubly bridged iron with pyrazolate ligands. An original DFT study at both the molecular and extended solid levels is carried out for this complex system with the purpose of identifying the magnetic interactions and chemical bonding characteristics. From molecular calculations, the exchange parameter J is obtained, pointing to the expected weakly antiferromagnetic ground state. The IR and Raman spectra have been calculated with relevant assignments, namely for the stretching modes. Computations for the extended solid in different magnetic configurations point to the total moment of 4μB·fu-1, identifying Fe as divalent in high spin configuration, in accordance with a weak tetrahedral crystal field. From relative energies the ground state is antiferromagnetic. Analyses of the chemical bonding (COOP) and of electron localization function (ELF) illustrate the interactions between Fe and the cycle as well as within the pz cycle.