The non-centrosymmetric polymorph of (quinolin-8-ol-κ2 N,O)(quinolin-8-olato-κ2 N,O)silver(I)

The title compound, [Ag(C9H6NO)(C9H7NO)], crystallizes as a non-centrosymmetric polymorph. The structure was previously reported by Wu et al. [(2006). Acta Cryst. E62, m281–m282] in the centrosymmetric space group Pbcn. The AgI ion displays a distorted tetrahedral coordination geometry defined by two N and two O atoms from a neutral quinolin-8-ol ligand (HQ) and a deprotonated quinolin-8-olate anion (Q−). The dihedral angle between the two ligands is 47.0 (1)°. Strong O—H⋯O hydrogen bonds link the molecules into a supramolecular chain along the a-axis direction.

The title compound, [Ag(C 9 H 6 NO)(C 9 H 7 NO)], crystallizes as a non-centrosymmetric polymorph. The structure was previously reported by Wu et al. [(2006). Acta Cryst. E62, in the centrosymmetric space group Pbcn. The Ag I ion displays a distorted tetrahedral coordination geometry defined by two N and two O atoms from a neutral quinolin-8ol ligand (HQ) and a deprotonated quinolin-8-olate anion (Q À ). The dihedral angle between the two ligands is 47.0 (1) . Strong O-HÁ Á ÁO hydrogen bonds link the molecules into a supramolecular chain along the a-axis direction.

Experimental
A methanol solution (15 ml) of 8-hydroxyquinoline(HQ) (0.075 g,0.5 mmol) was mixed with an aqueous solution (5 ml) of AgNO 3 (0.085 g, 0.5 mmol). Ammonia solution was dropped into the mixture under stirring until it was almost clear.
Then it was filtered. Yellow single crystals, suitable for X-ray, were obtained after several days.

Refinement
The H atoms on C atoms and O atom were placed in idealized positions and refined as riding atoms with C-H = 0.93 Å and O-H = 0.84 (2) Å, with U iso (H) = 1.2U eq (C).  The molecular structure of (I).

Figure 2
View of the hydrogen-bonding chain of (1). Hydrogen bonds are drawn as dashed lines.  View of the packing. H atoms have been omitted for clarity.

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.