$^3_\infty$ [Tl 2 Zn(ADC) 2 (H 2 O) 2 ]: the First Coordination Polymer with Acetylenedicarboxylate (ADC 2– ) as Bridging Ligand containing two Different Metal Ions

From an aqueous solution containing ZnCO 3 , Tl(CH 3 COO), and acetylenedicarboxylic acid (H 2 ADC: HOOC‐C≡C‐COOH) single crystals of $^3_\infty$ [Tl 2 Zn(ADC) 2 (H 2 O) 2 ] ( 1 ) were obtained. Compound 1 crystallizes in triclinic space group P $\bar{1}$ with Z = 1. A slightly distorted octahedral ZnO 6 coordination and a very unsymmetric TlO 6 coordination (Tl–O < 321 pm) are found, the latter probably caused by a stereochemically active lone pair at Tl + . These polyhedra are connected by the ADC 2– linker to form a 3D network structure. Additionally, hydrogen bonds are formed, which involve the water molecules (O ··· O starting at 274 pm). These are only coordinated to Zn 2+ . Compound 1 is the first coordination polymer of ADC 2– , which contains two different metal ions.