Crystal Structure and Solid-State Reactivity of a Cd(II) Polymeric Complex with Acetylenedicarboxylic Acid

The novel one-dimensional coordination polymer [Cd(ADC)(H 2 O) 3 ] H 2 O, where ADC 2 - = acetylenedicarboxylate dianion, was synthesized and characterized by single-crystal X-ray diffraction. The titled compound crystallizes in the monoclinic system, P 2 1 / n, a = 6.908(1) Å, b = 7.946(1) Å, c = 16.390(1) Å, β = 100.21(1)°, V = 885.4(2) Å 3, and Z = 4. The structure is made up of metal−organic chains linked by hydrogen bonds to form channels along the b axis. The carbon−carbon triple bonds are in close proximity (3.27 Å) along the a axis. This induces, upon heating, polymerization with formation of conjugated polycarboxylic chains. Detailed EPR studies have been performed in order to understand the polymerization process.