(NH 4) 2(C 4O 4), an anhydrous salt of acetylenedicarboxylic acid

• Published in: Solid state sciences Vol. 8; no. 3; pp. 353 - 358
• Main Authors: Stein, Irena, Näther, Christian, Ruschewitz, Uwe
• Format: Journal Article
• Language: English
• Published: Paris Elsevier Masson SAS 01.03.2006; Elsevier
• Subjects: Acetylenedicarboxylates; Aliphatic, non-condensed and condensed benzenic, and alicyclic compounds; Ammonium salts; Condensed matter: structure, mechanical and thermal properties; Coordination polymer; Crystal structure; Exact sciences and technology; Organic compounds; Physics; Structure of solids and liquids; crystallography; Structure of specific crystalline solids; Thermal analysis; Thermal expansion; thermomechanical effects; Thermal expansion; thermomechanical effects and density; Thermal properties of condensed matter; Thermal properties of crystalline solids; Ammonium salts; Thermal analysis; Acetylenedicarboxylates; Coordination polymer; Crystal structure; Temperature dependence; Thermal decomposition; Thermogravimetry; Mass spectroscopy; Differential thermal analysis; Carboxylic acids; XRD; Experimental study; Acetylene; Monocrystals; Anhydrous compound; Aqueous solutions; Morphology; Organic salt; Thermal expansion coefficient; Organic compounds
• ISSN: 1293-2558; 1873-3085
• DOI: 10.1016/j.solidstatesciences.2006.02.004

Single crystals of anhydrous ammonium acetylenedicarboxylate ((NH 4) 2(C 4O 4), 1) were isolated from a precipitate crystallizing from an aqueous ammonia solution containing acetylenedicarboxylic acid. The crystal structure of 1 ( C 2 / m , Z = 2 ) consists of ordered ammonium cations, which are connected via N H⋯O hydrogen bonds (N O: 2.826 and 2.947 Å) to four oxygen atoms from four symmetry related acetylenedicarboxylates. The coordination by the bifunctional carboxylates leads to a three-dimensional framework structure. Coupled TGA/DTA/MS measurements show that 1 decomposes completely at about 450 K releasing NH 3, CO 2, and C 2H 2. No order–disorder transition occurs in the temperature range between 20 K and the decomposition temperature. In contrast to Sr(C 4O 4), the other known anhydrous acetylenedicarboxylate, no negative thermal expansion is found below room temperature.