Poly[[[μ-1,4-bis(pyridin-4-ylcarbonyl)piperazine-κ2N:N′][μ-2-(2-carboxylatoeth-1-en-1-yl)benzoato-κ2O:O2]zinc(II)] 2.5 hydrate]: a tri-periodic coordination polymer with a dimer-based six-connected pcu topology

The title compound, {[Zn(C10H6O4)(C16H16N4O2]·2.5H2O}n, contains five-coordinate ZnII ions intermediate between square-pyramidal and trigonal–bipyramidal coordination environments. The ZnII ions are connected by 2-carboxycinnamate (cca) ligands and N,N′-bis-(pyridine-4-carboxamido)piperazine (4-pcap) ligands to construct a non-interpenetrated, tri-periodic coordination polymer with embedded [Zn2(OCO)2] dimeric units. Treating these as six-connected nodes reveals an overall (41263) pcu topology. One of the 4-pcap piperazinyl rings is disordered equally over two sets of crystallographic positions.