Bis[μ-N-(pyridin-2-ylmethyl)pyridin-3-amine-κ2 N:N′]disilver(I) bis(perchlorate) dimethyl sulfoxide disolvate

In the binuclear title compound, [Ag2(C11H11N3)2](ClO4)2·2C2H6SO, the complex cation is centrosymmetric, with the unique AgI cation coordinated by two pyridine N atoms from two symmetry-related N-(pyridine-2-ylmethyl)pyridine-3-amine ligands in a geometry slightly distorted from linear [N—Ag—N = 170.78 (9)°], resulting in the formation of a 16-membered cyclic dimer. The two pyridine rings coordinating to the AgI atom are almost perpendicular to each other [dihedral angle = 87.73 (10)°]. Intermolecular Ag⋯O interactions [3.149 (3) and 2.686 (3) Å], N—H⋯O and C—H⋯O hydrogen bonds and C—H⋯π interactions between the cyclic dimers and the anions or the solvent molecules lead to the formation of a three-dimensional supramolecular network.

In the binuclear title compound, [Ag 2 (C 11 H 11 N 3 ) 2 ](ClO 4 ) 2 Á-2C 2 H 6 SO, the complex cation is centrosymmetric, with the unique Ag I cation coordinated by two pyridine N atoms from two symmetry-related N-(pyridine-2-ylmethyl)pyridine-3amine ligands in a geometry slightly distorted from linear  ], resulting in the formation of a 16membered cyclic dimer. The two pyridine rings coordinating to the Ag I atom are almost perpendicular to each other [dihedral angle = 87.73 (10) ]. Intermolecular AgÁ Á ÁO interactions [3.149 (3) and 2.686 (3) Å ], N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds and C-HÁ Á Á interactions between the cyclic dimers and the anions or the solvent molecules lead to the formation of a three-dimensional supramolecular network.

Comment
In the development of silver(I) coordination polymers with fascinating structures, numerous symmetrical dipyridyl ligands with nitrogen donor atoms in the same positions on the two terminal pyridines are employed due to their easy synthesis (Lee et al., 2012;Leong & Vittal, 2011;Park et al., 2010). Despite the rapid growth in the Ag I coordination chemistry, however, the investigation of Ag I coordination polymers using unsymmetrical dipyridyl ligands with nitrogen donor atoms on different positions in the two terminal pyridines still remains lacking (Moon et al., 2013;Zhang et al., 2013). Herein, we report the crystal structure of the title compound prepared by the reaction of silver(I) perchlorate with the unsymmetrical dipyridyl ligand N-(pyridine-3-ylmethyl)pyridine-2-amine. This was synthesized by the reaction of 2aminopyridine and 3-pyridinecarboxaldehyde according to literature procedures (Foxon et al., 2002;Lee et al., 2008).
The binuclear cation of the title compound, [Ag 2 (C 11 H 11 N 3 ) 2 ](ClO 4 ) 2 (C 2 H 6 SO) 2 , is located on an inversion centre. In the crystal structure, the cyclic units interact with the ClO 4anions and the DMSO solvent molecules via intermolecular N-H···O and C-H···O hydrogen-bonds and C-H···π interactions (Table 1, Fig. 1). These interactions lead to the construction of a three-dimensional supramolecular network (Fig. 2).

Experimental
The ligand (N-(pyridin-3-ylmethyl)pyridine-2-amine) was prepared according to a procedure described by Foxon et al. (2002) and Lee et al. (2008). Crystals of the title compound suitable for X-ray analysis were obtained by vapor diffusion of diethyl ether into a DMSO solution of the white precipitate afforded by the reaction of the ligand with silver(I) perchlorate in the malar ratio 1:1 in methanol.

Refinement
All H atoms were positioned geometrically and refined using a riding model, with d(

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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq