Syntheses, structures, and magnetic properties of cyano- and phenoxide-bridged Fe(iii)–Mn(iii) tetrameric assemblies formed by blocked fac-Fe tricyanide with aliphatic rings

Abstract

Three tetranuclear clusters [(Tp^Me,mt3)Fe(CN)₃Mn(L)]₂ (1, L = 5-Clacphmen; 2, L = 5-Clsalen; 3, L = 5-MeOsalen; Tp^Me,mt3 = hydrotris(3-methyl-4,5-propylene-5-methylpyrazol-1-yl)borate) were prepared by assembling the fac-Fe tricyanide with the corresponding Mn Schiff bases. The assembled molecules are linked by cyanide and phenoxide bridges. Weak π–π contacts between molecules are evident in these clusters. Compounds 1–3 exhibit slow relaxation of the magnetization. The phenoxide linkers mediate ferromagnetic coupling between the Mn centers, which is ascribed to the long axial Mn–O* length. The overall magnetic exchange coupling nature of the Fe–CN–Mn route is accounted for by the important structural parameters of bridging pathways such as Mn–N_cyano length, Mn–N_cyano–C_cyano angle, and C_eq–Fe⋯Mn–N_eq (eq = equatorial) torsion angle.