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.