Synthesis, crystal structures, magnetic and luminescent properties of unique 1D p-ferrocenylbenzoate-bridged lanthanide complexes

Treatments of p-ferrocenylbenzoate [p-NaOOCH4C6Fc, Fc=(η5-C5H5)Fe(η5-C5H4)] with Ln(NO3)3·nH2O afford seven p-ferrocenylbenzoate lanthanide complexes {[Ln(OOCH4C6Fc)2(μ2-OOCH4C6Fc)2(H2O)2](H3O)}n [Ln=Ce (1), Pr (2), Sm (3), Eu (4), Gd (5), Tb (6) and Dy (7)]. X-ray crystallographic analysis reveals that the isomorphous complexes {[Ce(OOCH4C6Fc)2(μ2-OOCH4C6Fc)2(H2O)2](H3O)}n (1) and {[Pr(OOCH4C6Fc)2(μ2-OOCH4C6Fc)2(H2O)2](H3O)}n (2) form a unique 1D double-bridged infinite chain structure bridged by μ2-OOCH4C6Fc groups. Each Ln(III) ion adopts a dodecahedron coordination environment with eight coordinated oxygen atoms from two terminal monodentate coordinated FcC6H4COO− units, two terminal monodentate coordinated H2O molecules and four μ2-−OOCH4C6Fc units. The luminescent spectra reveal that only 4 and 6 exhibit characteristic emissions of lanthanide ions, Eu(III) and Tb(III) ions, respectively. The variable-temperature magnetic properties of 5 and 7 suggest that a ferromagnetic coupling between spin carriers may exist in 5.