Synthesis, Structure, and Magnetic Properties of Three 1D Chain Complexes Based on High-Spin Metal–Cyanide Clusters: [Mn^III₆M^III] (M = Cr, Fe, Co)

On the basis of high-spin metal–cyanide clusters of Mn^III₆M^III (M = Cr, Fe, Co), three one-dimensional (1D) chain complexes, [Mn(salen)]₆[Cr(CN)₆]₂·6CH₃OH·H₂O (1), [Mn(5-CH₃)salen)]₆[Fe(CN)₆]₂·2CH₃CN·10H₂O (2), and [Mn(5-CH₃)salen)]₆[Co(CN)₆]₂·2CH₃CN·10H₂O (3) [salen = N,N′-ethylenebis(salicylideneiminato) dianion], have been synthesized and characterized structurally as well as magnetically. Complexes 2 and 3 are isomorphic but slightly different from complex 1. All three complexes contain a 1D chain structure which is comprised of alternating high-spin metal–cyanide clusters of [Mn₆M]³⁺ and a bridging group [M(CN)₆]^3– in the trans mode. Furthermore, the three complexes all exhibit extended 3D supramolecular networks originating from short intermolecular contacts. Magnetic investigation indicates that the coupling mechanisms are intrachain antiferromagnetic interactions for 1 and ferromagnetic interactions for 2, respectively. Complex 3 is a magnetic dilute system due to the diamagnetic nature of Co^III. Further magnetic investigations show that complexes 1 and 2 are dominated by the 3D antiferromagnetic ordering with T_N = 7.2 K for 1 and 9.5 K for 2. It is worth noting that the weak frequency-dependent phenomenon of AC susceptibilities was observed in the low-temperature region in both 1 and 2, suggesting the presence of slow magnetic relaxations.