ChemInform Abstract: Synthesis and Characterization of Monometallic and Bimetallic Mixed-Ligand Complexes of Iron(II) Containing 2,2′-Bipyrimidine or 2,3-Bis(2-pyridyl)pyrazine.

ChemInform Abstract

The monometallic compounds (I) are prepared by published methods and the binuclear complexes (II) by reaction of the ligands with FeCl₂ and KCN in boiling water. By use of chromatography on an ion-exchange column or aqueous gel filtration chromatography it is possible to separate (II) from a mixture of products. The complexes are stable in aqueous solution, electronic spectra indicate intense MLCTtransitions in the visible region. The species (I) display one reversible oxidation (cyclic voltammetry and coulometry) corresponding to the Fe(III)/Fe(II) couple, while two reversible oxidations are observed for (II). The results show that the bis(pyridyl)pyrazine ligand may be more suitable than bipyrimidine in the preparation of mixed-metal bimetallic complexes since it significantly lowers the steric crowding without reducing the interaction between the metal centers.