Magnetic properties of cyano-bridged Ln3+-M3+ complexes.: Part I:: Trinuclear complexes (Ln3+ = La, Ce, Pr, Nd, Sm;: M3+ = FeLS, Co) with bpy as blocking ligand

The reaction of Ln(NO3)(3(aq)) with K-3[Fe(CN)(6)] or K-3[Co(CN)(6)] and 2,2'-bipyridine in water/ethanol led to eight trinuclear complexes: trans-[M(CN)(4)(mu-CN)(2){Ln(H2O)(4)(bPY)(2)}(2)] [M(CN)(6)]center dot 8H(2)O (M = Fe3+ or Co3+, Ln = La3+, Ce3+, Pr3+, Nd3+, and SM3+). The structures for the eight complexes [La2Fe] (1), [Ce2Fe] (2), [Pr2Fe] (3), [Nd2Fe] (4), [Ce2Co] (5), [Pr2Co] (6), [Nd2Co] (7), and [SM2Co] (8) have been solved; they crystallize in the triclinic space group P1 and are isomorphous. They exhibit a supramolecular 3D architecture through hydrogen bonding pi-pi and stacking interactions. A stereochemical study of the nine-vertex polyhedra of the lanthanide ions, based on continuous shape measures, is presented. No significant magnetic interaction was found between the lanthanide(Ill) and the iron(Ill) ions.