A new two-dimensional manganese(II) coordination polymer based on thiophene-3,4-dicarboxylic acid

A novel manganese coordination polymer, poly[(mu(5)-thiophene-3,4-dicarboxylato)manganese(II)], [Mn(C6H2O4S)](n), was synthesized hydrothermally using 3,4-thiophenedicarboxylate (3,4-tdc(2-)) as the organic linker. The asymmetric unit of the complex contains an Mn2+ cation and one half of a deprotonated 3,4-tdc(2-) anion, both residing on a twofold axis. Each Mn2+ centre is six-coordinated by O atoms of bridging/chelating carboxylate groups from five 3,4-tdc(2-) anions, forming a slightly distorted octahedron. The Mn2+ centres are bridged by 3,4-tdc(2-) anions to give an infinite two-dimensional layer which incorporates one-dimensional Mn-O gridlike chains, and in which the 3,4-tdc(2-) anion adopts a novel hexadentate chelating and mu(5)-bridging coordination mode. The fully deprotonated 3,4-tdc(2-) anion exhibits unexpected efficiency as a ligand towards the Mn2+ centres, which it coordinates through all of its carboxylate O atoms to provide the novel coordination mode. The IR spectrum of the complex is also reported.