A series of novel metal-ferrocenedicarboxylate coordination polymers: crystal structures, magnetic and luminescence properties

Novel two-dimensional layered lanthanide(III)-ferrocenedicarboxylate coordination polymers {[M(η²-O₂CFcCO₂-η²)(μ₂-η²-O₂CFcCO₂-η²-μ₂)_0.5(H₂O)₂]·mH₂O}_n (Fc=(η⁵-C₅H₄)Fe(η⁵-C₅H₄), M=Tb³⁺, m=2, 1; M=Eu³⁺, m=2, 2; M=Y³⁺, m=1, 3) with trapezium-shaped units and one-dimensional wave-shaped Cd(II)-ferrocenedicarboxylate polymer {[Cd(η²-O₂CFcCO₂-η²)(H₂O)₃]·4H₂O}_n (4) have been prepared and structurally characterized by single crystal diffraction. In polymers 1-3, each central metal ion (Tb(III), or Eu(III) or Y(III)) is located in a pseudo-capped-tetragonal prism coordination geometry, and ferrocenedicarboxylate anion ligands have two coordination modes (bidentate-chelating mode and tridentate-bridging mode). The magnetic behaviors for 1 and 2 are studied in the temperature range of 5.0-300 K. The results show that the paramagnetic behavior of 2 is mainly due to the effective spin-orbital coupling between the ground and excited states through the Zeeman perturbation, and the weak magnetic interaction between Eu³⁺ centers can be observed. In addition, compared with sodium ferrocenedicarboxylate, the fluorescent intensities of the polymers 1-4 are enhanced in the solid state.