Beschreibung:
<jats:title>Abstract</jats:title><jats:p>Planar bis(1,2‐dithiooxalato)nickelates(II) react in aqueous solutions of lanthanide ions to form pentanuclear, heterobimetallic complexes of the general composition [{Ln(H<jats:sub>2</jats:sub>O)<jats:sub>n</jats:sub>}<jats:sub>2</jats:sub>{Ni(dto)<jats:sub>2</jats:sub>}<jats:sub>3</jats:sub>]·x H<jats:sub>2</jats:sub>O (Ln = Y<jats:sup>3+</jats:sup>, La<jats:sup>3+</jats:sup>−Lu<jats:sup>3+</jats:sup>; n = 4 or 5; x = 9−12). With [{Ce(H<jats:sub>2</jats:sub>O)<jats:sub>5</jats:sub>}<jats:sub>2</jats:sub>{Ni(S<jats:sub>2</jats:sub>C<jats:sub>2</jats:sub>O<jats:sub>2</jats:sub>)<jats:sub>2</jats:sub>}<jats:sub>3</jats:sub>]·<jats:italic>x</jats:italic>H<jats:sub>2</jats:sub>O (<jats:italic>x</jats:italic> = 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 Ce<jats:sub>2</jats:sub>Ni<jats:sub>3</jats:sub> complex crystallizes with the unit cell parameters: monoclinic in <jats:italic>P</jats:italic>2<jats:sub>1</jats:sub>/<jats:italic>c</jats:italic> with <jats:italic>a</jats:italic> = 10.3894(6), <jats:italic>b</jats:italic> = 11.6000(7), <jats:italic>c</jats:italic> = 20.8964(11) Å, <jats:italic>β</jats:italic> = 98.431(4)° and <jats:italic>Z</jats:italic> = 2. The channels and cavities appearing in the crystal packing of the complex molecules are occupied by uncoordinated water molecules. The Eu<jats:sub>2</jats:sub>Ni<jats:sub>3</jats:sub> and Tb<jats:sub>2</jats:sub>Ni<jats:sub>3</jats:sub> complexes were investigated in steady‐state and time‐resolved luminescence measurements. Luminescence of the isostructural Tb<jats:sub>2</jats:sub>Ni<jats:sub>3</jats:sub> complex has been observed at room temperature.</jats:p>