Crystal structure of an AgI intercalation compound: catena-poly[[silver(I)-μ-N-(pyridin-3-ylmethyl)pyridin-3-amine-κ2 N:N′] hexafluoridophosphate acetonitrile disolvate]

The AgI atom in the title compound is two-coordinate, being bound to two pyridine N atoms from two N-(pyridin-3-ylmethyl)pyridin-3-amine ligands in a slightly distorted linear fashion. Each AgI ion bridges the dipyridyl-type ligands to form polymeric zigzag chains. The chains are connected via Ag⋯Ag and π–π interactions, forming a corrugated layer parallel to (01). Acetonitrile solvent molecules and PF6 − anions are intercalated between these layers. Several intermolecular N/C—H⋯F hydrogen bonds lead to formation of a three-dimensional supramolecular network.

The asymmetric unit in the title compound, [Ag(C 11 H 11 N 3 )]PF 6 Á2CH 3 CN or {[AgL]ÁPF 6 Á2CH 3 CN} n , L = N-(pyridin-3-ylmethyl)pyridin-3-amine, comprises one Ag I atom, one L ligand, two acetonitrile solvent molecules and one PF 6 À anion disordered over two orientations in a 0.567 (11):0.433 (11) ratio. Each Ag I atom is coordinated by two pyridine N atoms from two L ligands in a slightly distorted linear coordination geometry  ]. Each L ligand bridges two Ag I ions, resulting in the formation of a zigzag chain propagating along the [101] direction. In the crystal, AgÁ Á ÁAg contacts [3.3023 (5) Å ] and intermolecularstacking interactions [centroid-tocentroid distance = 3.5922 (15) Å ] between the pyridine rings link these chains into a corrugated layer parallel to the (101) plane. The layers are stacked with a separation of 10.4532 (5) Å , and acetonitrile solvent molecules and PF 6 À anions as guests are intercalated between the layers. The layers are connected through several N/C-HÁ Á ÁF hydrogen bonds and P-FÁ Á Á interactions [FÁ Á Áring centroid = 3.241 (8) Å ] between the layer and the intercalated guests and between the intercalated guests, forming a three-dimensional supramolecular network.

Chemical context
Silver coordination polymers based on dipyridyl-type ligands have been widely exploited due to the intriguing topologies and the fascinating properties caused by a variety of coordination geometries and d 10 electronic configurations of the Ag I ion (Leong & Vittal, 2011;Moulton & Zaworotko, 2001;Wang et al., 2012). In particular, Ag I ions have a preference for a linear two-coordinate geometry and can serve to link bridging dipyridyl-type ligands to form polymeric chains. Based on this concept, we have focused our attention on the development of one-dimensional Ag I coordination polymers with dipyridyltype ligands. Up to date, we have reported several Ag I coordination polymers with interesting topologies involving zigzag (Moon et al., 2016), helical (Moon et al., 2014 and double helical (Lee et al., 2015) structures. In an extension of our research, the title compound was prepared by the reaction of silver(I) hexafluoridophosphate with a dipyridyl typeligand, namely N-(pyridin-3-ylmethyl)pyridin-3-amine (L), synthesized according to a literature procedure (Lee et al., 2013). Herein, we report on the crystal structure of the title compound in which lattice solvent molecules and anions as ISSN 2056-9890 guests are intercalated between the layers formed by intermolecular interactions between zigzag -(Ag-L) n -chains.

Structural commentary
The molecular components of the title structure are shown in Fig. 1. The asymmetric unit comprises one Ag I atom, one L ligand, two acetonitrile solvent molecules, and one hexafluoridophosphate anion disordered over two orientations in a 0.567 (11):0.433 (11) ratio. The silver(I) atom is coordinated by two pyridine N atoms (N1 and N2) from two symmetryrelated L ligands, leading to the formation of an infinite zigzag chain propagating along the [101] direction. Thus, the Ag I atom is two-coordinated in a slightly distorted linear coordination geometry [N1 i -Ag1-N2 = 170.55 (8) ; symmetry code: (i) x + 1 2 , Ày + 1 2 , z + 1 2 ; Table 1]. This distortion from linear geometry may be caused by AgÁ Á ÁN interactions between the Ag I ion and two acetonitrile N atoms [Ag1Á Á ÁN4 = 2.792 (4), Ag1Á Á ÁN5 = 2.815 (4) Å ; black dashed lines in Fig. 1]. The two pyridine rings coordinated to the Ag I center are tilted slightly, by 6.29 (15) with respect to each other. In the chain, the Ag I atoms are separated by 11.1009 (3) Å along the L linker which adopts a stretched trans conformation with the C2-N3-C6-C7 torsion angles being 174.7 (3) .

Figure 2
The two-dimensional network formed through AgÁ Á ÁAg contacts (red dashed lines) and intermolecularstacking interactions (yellow dashed lines). Acetonitrile solvent molecules, the PF 6 À anions and H atoms have been omitted for clarity.

Synthesis and crystallization
The L ligand was synthesized according to a literature method (Lee et al., 2013). Slow evaporation of an acetonitrile solution of the L ligand with AgPF 6 in the molar ratio 1:1 afforded colourless block-like X-ray quality single crystals of the title compound.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3. The PF 6 À anion is disordered over two orientations in a 0.567 (11):0.433 (11) ratio. The amine H atom was located from a difference-Fourier map and freely refined [N-H = 0.84 (3) Å ]. All other H atoms were positioned geometrically and refined as riding: C-H = 0.95 Å for Csp 2 -H, 0.99 Å for methylene C-H and 0.98 Å for methyl C-H with U iso (H) = 1.5U eq (C-methyl) and 1.2U eq (C) for other C-bound H atoms.

catena-Poly[[silver(I)-µ-N-(pyridin-3-ylmethyl)pyridine-3-amine-κ 2 N:N′] hexafluoridophosphate acetonitrile disolvate]
Crystal data Special details Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.