Structure of a Coordination Polymer Reminiscent of the Pleated Sheets Observed in Polypeptides: Diaqua(2,2'-bipyridine-3,3'-dicarboxylato)copper(II)

Abstract

The preparation and crystal structure of [Cu(BPDC)(H 2 O) 2 ) (BPDC = C 12 H 6 N 2 O 2− 4 , 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 headto-tail alignment {i.e. catena-poly[diaquacopper(II)-μ-(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 hydrogenbonding interactions with water molecules