Iron (II) isothiocyanate complexes with substituted pyrazines: Experimental and theoretical views on their electronic structure

Abstract

Synthesis, structural, magnetic, Mössbauer and thermal studies of isothiocyanate iron (II) complexes with substituted pyrazines (iodo-, bromo- and amino-derivatives) are discussed here. Complexes with iodo- and bromo-derivatives were found to have the composition [Fe(Ipz)2(SCN)2(H2O)2]·2Ipz (1) and [Fe(Brpz)2(SCN)2(H2O)2]·2Brpz (2), whereas in the case of amino-functionalized pyrazine the formation of [Fe(NH2pz)4(SCN)2] (3) was observed. 3D organization of the molecular complexes is stabilized within different hydrogen, halogen and lone pair–π interactions. Spin state of iron (II) ions in 1–3 was determined as high spin by Mössbauer and magnetic measurements. DFT calculations for the obtained iron (II) complexes were carried out to analyze the electronic structure and to support experimentally measured Mössbauer parameters with theoretical predictions.