Cyanide- and phenoxo-bridged heterobimetallic Fe(III)-Mn(III) complexes: Synthesis, crystal structures and magnetic properties

Abstract

By employing two mer-tricyanidoiron(III) precursors [Ph4P][FeIII(pcq)(CN)3] and [Ph4P][FeIII(pzq)(CN)3] as building blocks and a salen-tpye Schiff-base manganese (III) compound as assembling segment, two tetranuclear cyanide- and phenoxo- bridged heterobimetallic Fe(III)-Mn(III) complexes {[Mn(saltmen)] [Fe(pcq)(CN)3]}2⋅2CH3OH (1) and {[Mn(saltmen)] [Fe(pzq)(CN)3]}2⋅2CH3OH (2) (pcq = 8-(pyridine-2-carboxamido, pzq = 8-(pyrazine-2-carboxamido, saltmen2− = N,N’-(1,1,2,2-tetramethylethylene)bis(salicylideneaminato)dianion) have been synthesized and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Single x-ray analysis reveals their isostructural cyanide-bridged Fe(III)-Mn(III) binuclear structure. The binuclear entity is self-complementary through phenoxo oxygen from the neighbouring complex, giving cyanide- and phenoxo- bridged tetranuclear structure. Furthermore, under the help of the intermolecular π- π interaction, these two complexes can be constructed into 1D infinite chain supramolecular structure. Investigation over magnetic susceptibilities reveals the overall ferromagnetic coupling between the adjacent Fe(III) and Mn(III) ions bridged by cyanide group with J = 5.34 cm−1 and 5.55 cm−1 for complexes 1 and 2, respectively. Two tetranuclear cyanide- and phenoxo- bridged Fe(III)-Mn(III) complexes have been synthesized with mer-tricyanoiron(III) as building blocks and a Schiff-base manganese(III) compound as assembling segment and characterized by elemental analysis, IR spectroscopy and X-ray structure determination. Investigation over the magnetic susceptibilities reveals the ferromagnetic coupling between Fe(III)-Mn(III) through the cyanide bridge.