Synthesis, Crystal Structures, and Magnetic Properties of Three Novel Ferrocenecarboxylato-Bridged Lanthanide Dimers

Three novel ferrocenecarboxylato-bridged lanthanide dimers [Gd2(μ2-OOCFc)2(OOCFc)4(MeOH)2(H2O)2]·2MeOH·2H2O (1) (Fc = (η5-C5H5)Fe(η5-C5H4)), [Nd2(μ2-OOCFc)2(OOCFc)4(H2O)4]·2MeOH·H2O (2), and [Y2(μ2-OOCFc)2(OOCFc)4(H2O)4]·2MeOH (3) have been synthesized and characterized by single-crystal X-ray crystallography. In
each complex, two Ln(III) (Ln = Gd, Nd, or Y) ions are bridged by two ferrocenecarboxylate anions as asymmetrically
bridging ligands, leading to dimeric cores, [Ln2(μ2-OOCFc)2]; each Ln(III) ion has an irregular polyhedral coordination
environment with nine coordinated oxygen atoms derived from the ferrocenecarboxylate ligands and coordinated
solvent molecules. In the solid-state structure of compound 1, [Gd2(μ2-OOCFc)2(OOCFc)4(MeOH)2(H2O)2] groups
are joined together by hydrogen bonds forming a two-dimensional network. Both compounds 2 and 3 show one-dimensional chain structures by hydrogen bonding; they are different from 1. Magnetic measurements show
unexpected ferromagnetic coupling between the gadolinium(III) ions; the best fittings to the experimental magnetic
susceptibilities gave J = 0.006 cm-1 and g = 2.0 for 1. The magnetic behavior for 2 was also studied in the
temperature range of 1.8−300 K.