STRUCTURE OF A COORDINATION POLYMER REMINISCENT OF THE PLEATED SHEETS OBSERVED IN POLYPEPTIDES - DIAQUA-(2,2'-BIPYRIDINE-3,3'-DICARBOXYLATO)-COPPER(II)

The preparation and crystal structure of [Cu(BPDC)-(H2O)(2)] (BPDC = C12H6N2O42-, the dianion of 2,2-bipyridine-3,3'-dicarboxylic acid) are described, The Cu atom is pentacoordinate; the BPDC ligands and water molecules form a distorted square-pyramidal geometry about the metal atom, BPDC residues linking Cu atoms to give a coordination polymer with head-to-tail alignment {i.e. catena-poly[diaquacopper(II)-mu-(2,2'-bipyridine-3,3'-dicarboxylato-N,N':O)]}. Adjacent antiparallel chains are cross-linked by hydrogen bonds in a sheet-like structure reminiscent of the pleated sheets observed in polypeptides, The non-metallated O atoms of the carboxylate groups participate in hydrogen-bonding interactions with water molecules.