catena-Poly[[[aqua(1,10-phenanthroline-κ2 N,N′)zinc]-μ-acetylenedicarboxylato-κ2 O 1:O 2] monohydrate]

In the title complex, {[Zn(C4O4)(C12H8N2)(H2O)]·H2O}n, the pentacoordinated ZnII ion is bound to two N atoms of the 1,10-phenanthroline ligand, two O atoms from two bridging acetylenedicarboxylate anions and a water O atom in a distorted trigonal–bipyramidal geometry. The crystal structure is characterized by polymeric zigzag chains running parallel to [2-10] and is stabilized by O—H⋯O hydrogen bonds.

In the title complex, {[Zn(C 4 O 4 )(C 12 H 8 N 2 )(H 2 O)]ÁH 2 O} n , the pentacoordinated Zn II ion is bound to two N atoms of the 1,10-phenanthroline ligand, two O atoms from two bridging acetylenedicarboxylate anions and a water O atom in a distorted trigonal-bipyramidal geometry. The crystal structure is characterized by polymeric zigzag chains running parallel to [210] and is stabilized by O-HÁ Á ÁO hydrogen bonds.

Experimental
Crystal data [Zn(C 4 Table 1 Hydrogen-bond geometry (Å , ). The design and structural control of polymetallic complexes is an area of interest owing to wide potential applications (Winpenny, 2001;Swiegers et al., 2000). In this context, acetylenedicarboxylate is a particularly attracting ligand as a building block of polymeric metal complexes (Hermann et al., 2011;Lin et al., 2011;Zheng et al., 2010). I report herein on a polymeric zinc complex based on 1,10-phenanthroline and the acetylenedicarboxylate anion. The Zn(II) ion is bound to two nitrogen atoms of the 1,10-phenanthroline ligand, two oxygen atoms each belonging to an acetylenedicarboxylate anion and an oxygen atom of a water molecule ( Figure 1). The geometry is distorted trigonal bipyramidal where the equatorial positions are occupied by the two carboxylate oxygen atoms and one nitrogen atom. The two acetylenedicarboxylate anions are each located on an inversion center and bridging Zn(II) ions to generate a zigzag chain structure parallel to [2 1 0] ( Figure 2). The coordinated water molecule belonging to one chain interacts with a carbonyl oxygen of an adjacent chain, giving rise to eight-membered [Zn-(O···H-O) 2 -Zn] inter-chain rings with a chair configuration.
One crystallization water molecule in the lattice has hydrogen bonding interactions connecting three adjacent chains by interacting with two carbonyl oxygen atoms of the first and second chain respectively in addition to a hydrogen atom of the coordinated water molecule of the third chain. A six-coordinate octahedral pyridine complex with similar hydrogen bonding interactions has been reported (Stein et al., 2009).

Experimental
Acetylenedicarboxylic acid (0.2 mmol, 0.0228 g) and 1,10-phenanthroline (0.2 mmol, 0.0397 g) were mixed in 2 ml e thanol. A clear solution was obtained upon addition of an aqueous solution (2 ml) of Zn(NO 3 ) 2 .6H 2 O (0.2 mmol, 0.0595 g). The pH was then adjusted to 4.4 using NaOH (0.010 M) and the solution was filtered. Colorless crystals suitable for X-ray diffraction were obtained after few days by slow evaporation of the filtrate.

Refinement
H atoms of the two water molecules were located on a difference Fourier map and refined isotropically with distance restraints of O-H = 0.84 (2) Å. All other H atoms were placed in calculated positions with a C-H distance of 0.93 Å and U iso (H) = 1.2U eq (C).

Special details
Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s involving l.s. planes. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.