Pyrazine-2,3-dicarboxylate-bridged polymeric and dinuclear complexes involving decameric water clusters

Two copper(II) complexes of pyrazine-2,3-dicarboxylate (H₂pzdc) with 2-aminopyridine (apy), {(Hapy)₂[Cu(μ-pzdc)₂]} _n (1) and 1,10-phenanthroline (phen), [Cu₂(μ-pzdc)(phen)₄][N(CN)₂]₂?·9H₂O (2) have been synthesized and structurally characterized. Complex 1 consists of a pyrazine-2,3-dicarboxylate bridging across a double chain, while 2 exists as a dinuclear complex in which two Cu(II) ions are bridged by pzdc via different coordination modes. One Cu(II) ion in the binuclear complex is a distorted octahedron, while the other Cu(II) is a distorted trigonal bipyramid. A chair-like decameric water cluster composed of two pentamers and a shared-edge tetramer is detected, which further associate into a 1-D tape with dicyanamide anions by hydrogen bonds.