Triangular Oxalate Clusters [W₃(μ₃-S)(μ₂-S₂)₃(C₂O₄)₃]^2- as Building Blocks for Coordination Polymers and Nanosized Complexes

The reaction of aqueous [W3S7(C2O4)3]2- with Ln3+ and Th4+ in a 1:1 molar ratio leads to oxalate-bridged heteropolynuclear molecular complexes and coordination polymers. La3+ and Ce3+ give a layered structure with big (about 1.8 nm) honeycomb pores which are filled with water molecules and lanthanide ions, in {[Ln(H2O)6]3[W3S7(C2O4)3]4}Br·xH2O (Ia and Ib). The smaller Pr3+, Nd3+, Sm3+, Eu3+, and Gd3+ ions give discrete nanomolecules [(W3S7(C2O4)3Ln(H2O)5)2(μ-C2O4)] (with a separation of about 3.2 nm between the most distant parts of the molecule), which are further united into zigzag chains by specific S2···Br- contacts to achieve the overall stoichiometry K[(W3S7(C2O4)3Ln(H2O)5)2(μ-C2O4)]Br·xH2O (IIa−IId). Th4+ gives K2[(W3S7(C2O4)3)4Th2(OH)2(H2O)10]·14.33H2O (III) with a nanosized discrete anion (with a separation of about 2.7 nm between the most distant parts of the molecule), in which two thorium atoms are bound via two hydroxide groups into the Th2(OH)26+ unit, and each Th is further coordinated by five water molecules and two monodentate [W3S7(C2O4)]2- cluster ligands. All compounds were characterized by X-ray structure analysis and IR spectroscopy. Magnetic susceptibility measurements in the temperature range of 2−300 K show weak antiferromagnetic interactions between two lanthanides atoms for compounds IIa, IIb, and IId. The thermal decomposition of Ia, Ib, and IIb was studied by thermogravimetry.