The coordination polymers poly[μ‐4,4′‐bipyridyl‐di‐μ‐formato‐copper(II)] and catena‐poly[[[diaqua(1‐benzofuran‐2,3‐dicarboxylato)copper(II)]‐μ‐1,2‐di‐4‐pyridylethane] dihydrate]

The title compounds, [Cu(CHO₂)₂(C₁₀H₈N₂)]_n, (I), and {[Cu(C₁₀H₄O₅)(C₁₂H₁₂N₂)(H₂O)₂]·2H₂O}_n, (II), are composed of one‐dimensional linear coordination polymers involving copper(II) ions and bidentate bipyridyl species. In (I), the polymeric chains are located on twofold rotation axes at (x, x, 0) and are arranged in layered zones centered at z = 0, , ½ and parallel to the ab plane of the tetragonal crystal. Weak coordination of the formate anions of one layer to the copper centers of neighboring layers imparts a three‐dimensional connectivity to this structure. In (II), the polymeric chains propagate parallel to the a axis of the crystal. Noncoordinated water molecules link the chains through O—H...O hydrogen bonding in directions perpendicular to c, imparting to the entire structure three‐dimensional connectivity. The metal ions adopt distorted octahedral and square‐based pyramidal environments in (I) and (II), respectively. This study indicates that, under the given conditions, extended coordination involves Cu^II centers associating with the bipyridyl ligands rather than with the competing benzofurandicarboxylate entities.