Poly[[[μ-1,4-bis-(pyridin-4-ylcarbon-yl)piperazine-κ 2 N : N '][μ-2-(2-carboxyl-atoeth-1-en-1-yl)benzoato-κ 2 O : O 2 ]zinc(II)] 2.5 hydrate]: a tri-periodic coordination polymer with a dimer-based six-connected pcu topology.

The title compound, {[Zn(C 10 H 6 O 4 )(C 16 H 16 N 4 O 2 ]·2.5H 2 O} n , contains five-coordinate Zn II ions inter-mediate between square-pyramidal and trigonal-bipyramidal coordination environments. The Zn II ions are connected by 2-carb-oxy-cinnamate (cca) ligands and N , N '-bis-(pyridine-4-carboxamido)-piperazine (4-pcap) ligands to construct a non-inter-penetrated, tri-periodic coordination polymer with embedded [Zn 2 (OCO) 2 ] dimeric units. Treating these as six-connected nodes reveals an overall (4 12 6 3 ) pcu topology. One of the 4-pcap piperazinyl rings is disordered equally over two sets of crystallographic positions.