Varying structural motifs in oxyanions (NO(3)(-), CO(3)(2-)) and phenoxyacetate (PhOAc(-)) bridged coordination polymers derived from alkoxo-bridged dicopper building blocks with {Cu(2)O(2)} core

Abstract

The oxyanions (NO(3)(-), CO(3)(2-)) and phenoxyacetate (PhOAc(-)) bridged three 1D-coordination polymeric chains, {[Cu(2)(mu-hep)(2)(mu-NO(3))](2)}(n) (1), {[Cu(2)(mu-hep)(2)(H(2)O)(2)]center dot 2H(2)O(mu-CO(3))}(n) (3) and {[Cu(2)(mu-hep)(2)(mu-PhOAc(-))](2)}(n) (2) (hep-H = 2-(2-hydroxyethyl)pyridine) have been synthesized. In 1-3 the alkoxide bridged dicopper building units, [Cu(m-hep)](2) with Cu(2)O(2) core, are linked via the respective anions. Detailed structural analysis reveals that in 1 or 2, two units of NO(3)(-) (1) or PhOAc 2 (2), respectively, bind with the four copper ions in two adjacent alkoxide bridged dimeric units in head-to-head and tail-to-tail fashion and the same binding mode continues along the polymeric chain. This in effect yields a 12-membered metallacyclic ring in between two dimeric core units. However, in 3 only one CO(3)(2-) group bridges the two copper centres associated with the two neighbouring alkoxide bridged dimeric units in head-to-tail mode which in turn forms a zig-zag polymeric chain. Two coordinated and two lattice water molecules from two adjacent polymeric layers in the structure of 3 form water tetramers. Furthermore, the interaction of water tetramer with the uncoordinated C=O group of the bridging CO(3)(2-) develops an additional zig-zag chain which is being trapped between the two outer zig-zag coordination polymeric chains in 3. The polymeric chains in 1-3 further develop a 2D-network pattern via an extensive non-covalent hydrogen bonding as well as C-H center dot center dot center dot pi and pi center dot center dot center dot pi interactions.