A Novel One-Dimensional Cyano-Bridged Ni3Fe2 Ferromagnet Constructed from Bimetallic Molecular Squares

Reaction of the complex [Ni(rac-CTH)]2+ (rac-CTH = rac-5,7,7,12,14,14-hexamethyl-1,4,8,11-tetraazacyclotetradecane) with [Fe(CN)6] 3- leads to a novel cyano-bridged Ni3Fe2 complex, {[Ni(rac-CTH)]3[Fe(CN)6]2}4. The structure consists of an alternating arrangement of {Fe(CN)6Ni(rac-CTH)}2 squares and trans-planar [Ni(rac-CTH)]2+ units bridged by cyanide groups to give a neutral 1D chain running along the a axis. Magnetic measurements reveal the occurrence of ferromagnetic coupling between FeIII and NiII ions and 3D magnetic ordering at 3 K due to interchain interactions. Canting of the moments is inferred from the low value of the magnetization of the saturation below Tc.