Completing the Series: New Coordination Networks of Composition 3 ∞ [ RE 2 (ADC) 3 (H 2 O) 6 ]·2H 2 O with RE = Pr, Nd, Sm, Eu, Tb, Dy, Ho, Er, Y and ADC 2– = Acetylenedicarboxylate ( – O 2 C–C≡C–CO 2 – )

The crystal structures of 3 ∞ [ RE 2 (ADC) 3 (H 2 O) 6 ] · 2H 2 O ( RE = Pr, Nd, Sm, Eu, Tb, Dy) were solved and refined from X‐ray single crystal data. They crystallize in a structure type already known for RE = La, Ce and Gd ( P 1 , no. 2, Z = 2), which is characterized by RE O 9 polyhedra forming dimeric units being the nodes of a 3D framework structure linked by ADC 2– anions ( – O 2 C–C≡C–CO 2 – = acetylenedicarboxylate). From synchrotron powder diffraction data it was shown that isostructural coordination networks are formed for RE = Ho, Er, Y, whereas for RE = Tm, Yb, Lu a new structure type crystallizing in a highly complex crystal structure with a large orthorhombic unit cell is found. All compounds are obtained by slow evaporation of an aqueous solution containing RE (OAc) 3 · x H 2 O and acetylenedicarboxylic acid (H 2 ADC). The coordination networks of composition 3 ∞ [ RE 2 (ADC) 3 (H 2 O) 6 ] · 2H 2 O were thoroughly investigated by thermal analysis and for RE = Eu, Tb, a strong red and green photoluminescence was observed and investigated by means of UV/Vis spectroscopy.