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

Three tetranuclear clusters [(Tp(Me,mt3))Fe(CN)(3)Mn(L)](2) (1, L = 5-Clacphmen; 2, L = 5-Clsalen; 3, L = 5-MeO-salen; 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 pi-pi 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-C N-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 center dot center dot center dot Mn-N-eq (eq = equatorial) torsion angle.