Towards a Rational Design of 3d-4f Heterometallic Coordination Polymers based on Mixed Valence Copper Centers

In the present work we report two new CuI/CuII-GdIII mixed valence heterometallic coordination polymers (HCP), [Gd(H2O)4CuIICuI(IDC)2] (1) and [Gd2(H2O)2(C2O4)2CuII(IDC)2CuI2(4,4'-bipy)]·4.5H2O (2) obtained under solvothermal synthesis using 1H-imidazole-4,5-dicarboxylic acid (H3IDC) as principal N,O-bifunctional organic linker. In both compounds, the stabilization of the CuI cations is achieved only by the coordination of N-atoms belonging to the organic ligands. While, (1) presents a 2D honeycomb network obtained by the coordination of single organic linker (IDC3-), (2) contains three different organic ligands (IDC3-, C2O42- and 4,4’-bipy), which allow the construction of a 3D network. From a magnetic point of view, (1) and (2) behave as simple paramagnets at high temperature, presenting ferromagnetic interactions below 50 K. A simplification of the extended networks to simple models permits to estimate the magnetic coupling between CuII…GdIII spin carriers. In this way, a positive magnetic coupling con...