Beschreibung:
<jats:p>Single crystals of dilithium‐acetylenedicarboxylate‐dihydrate, Li<jats:sub>2</jats:sub>ADC<jats:bold>·</jats:bold>2H<jats:sub>2</jats:sub>O (<jats:bold>1</jats:bold>), were isolated from a solid product formed by isothermal evaporation of an aqueous solution of LiOH und acetylenedicarboxylic acid (H<jats:sub>2</jats:sub>ADC). <jats:bold>1</jats:bold> crystallizes in the triclinic space group <jats:italic>P</jats:italic><jats:styled-content>1</jats:styled-content> with <jats:italic>Z</jats:italic> = 2. LiO<jats:sub>4</jats:sub> tetrahedra are interconnected by ADC<jats:sup>2–</jats:sup> anions and water molecules to form a 3D polymeric structure. Coupled TGA and DTA measurements show that <jats:bold>1</jats:bold> loses its two water molecules above 100 °C. Heating a polycrystalline sample of <jats:bold>1</jats:bold> at 140 °C for 2 h in an argon atmosphere leads to a significant change of the powder diffraction pattern indicating the formation of the new anhydrous coordination polymer dilithium‐acetylenedicarboxylate, Li<jats:sub>2</jats:sub>ADC (<jats:bold>2</jats:bold>). Its crystal structure was solved and refined from X‐ray powder diffraction data. <jats:bold>2</jats:bold> crystallizes in the orthorhombic space group <jats:italic>Fddd</jats:italic> (Z = 8). LiO<jats:sub>4</jats:sub> tetrahedra are interconnected by ADC<jats:sup>2–</jats:sup> anions to form a 3D polymeric structure.</jats:p>