Synthesis and Magneto‐Structural Studies of a New Family of 3d‐4f Ln‐TM Heterometallic Complexes

A new family of 3d‐4f Ln‐TM (Ln = lanthanide TM = transition metal) heterometallic [Ln─Co] complexes [Ln 2 Co(2,6‐dipic) 4 (H 2 O) 8 ]∙8H 2 O (Ln = La, Ce, Pr, Nd, Sm), (2,6‐dipic = pyridine‐2,6‐dicarboxylic acid anion) were synthesized, featuring a unique new Ln‐Co double heteronuclear structure. Structural analyses reveal that the complexes crystallize in monoclinic, space group C 2/c . The carboxyl(─COO) groups chelated one Ln 3+ ion ( anti ) and one bridging Co 2+ ion ( syn ), which conformed a syn–anti chelating mode. As a result, one Co 2+ ion connected two units of Ln 3+ as a syn–syn bridge forming a Z‐shaped 1D chain. From the study of the magneto‐structural, antiferromagnetic interaction between adjacent paramagnetic ions were found. The magnetic data of the complexes were fitted by different equations with a least‐squares refinement method to get an estimate on the strength of the antiferromagnetic exchange interaction, and to describe the spin‐orbit coupling.