Syntheses, crystal structures and magnetic properties of three cyanide-bridged iron(III)–manganese(II) binuclear complexes based on dicyanideferrite(III) building blocks

Abstract

Three cyanide-bridged FeIII–MnII binuclear complexes [Mn(phen)2Cl][Fe(bpmb)(CN)2]·H2O (1), [Mn(phen)2Cl][Fe(bpdmb)(CN)2]·H2O (2) and [Mn(phen)2Cl][Fe(bpClb)(CN)2]·3H2O·EtOH (3) [phen = 1,10-phenanthroline, bpmb2− = 1,2-bis(pyridine-2-carboxamido)-4-methyl-benzenate, bpdmb2− = 1,2-bis(pyridine-2-carboxamido)-4,5-dimethyl-benzenate, bpClb2− = 1,2-bis(pyridine-2-carboxamido)-4-chloro-benzenate)] have been synthesized by the reaction of Mn(phen)2Cl2 with K[Fe(L)(CN)2]. The syntheses, crystal structures and magnetic properties of the complexes have been investigated. Single-crystal X-ray diffraction analysis reveals that all three complexes are binuclear complexes and contain FeIII–C≡N–MnII linkages. Magnetic investigations indicate antiferromagnetic coupling between low-spin Fe(III) and high-spin Mn(II) centers through cyanide bridging, with JMnFe = −1.39(5) cm−1 for 1, JMnFe = −3.33(2) cm−1 for 2 and JMnFe = −1.96(5) cm−1 for 3. The magneto-structural relationships for cyanide-bridged FeIII–MnII systems are discussed based on binuclear FeIII–MnII and trinuclear FeIII–MnII–FeIII magnetic models.