Pentanuclear heterobimetallic 3d-4f-complexes - Structure and luminescence

Planar bis(1,2-dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H2O)(n)}(2){Ni(dto)(2)}(3)]center dot x H2O (Ln = Y3+, La3+-Lu3+; n = 4 or 5; x = 9-12). With [{Ce(H2O)(5)}(2){Ni(S2C2O2)(2)}(3)]center dot xH(2)O (x = 10-12) we were able to isolate another complex of this series as single crystals, which were characterized by X-ray structure analysis. Depending on the individual ionic radii of the lanthanide ions, the compounds crystallise in two different crystal systems. The Ce2Ni3 complex crystallizes with the unit cell parameters: monoclinic in P2(1)/c with a = 10.3894(6), b = 11.6000(7), e = 20.8964(11) angstrom, beta = 98.431(4)degrees and Z = 2. The channels and cavities appearing in the crystal packing of the complex molecules are occupied by uncoordinated water molecules. The Eu2Ni3 and Tb2Ni3 complexes were investigated in steady-state and time-resolved luminescence measurements. Luminescence of the isostructural Tb2Ni3 complex has been observed at room temperature.