catena-Poly[[silver(I)-μ-bis{2-[(E)-phenyldiazenyl]-1H-imidazol-1-yl}methane] trifluoromethanesulfonate]

The title compound, {[Ag(C19H16N8)](CF3SO3)}n, is a coordination polymer with cationic chain motif. The Ag+ cation is coordinated by two unsubstituted imidazolyl N atoms of two independent 2-paBIM ligands [2-paBIM is bis{2-[(E)-phenyldiazenyl]-1H-imidazol-1-yl}methane]. The shortest Ag⋯Ag separation in a cationic chain is 8.841 (2) Å and the dihedral angle between two 2-phenyldiazenyl-imidazole planes in the same ligand is 74.7 (3)°. Weak C—H⋯O interactions are seen in the crystal.


Related literature
For background to metal-organic frameworks, see: Batten & Robson (1998)

Experimental
Crystal data [Ag(C 19

Comment
The construction of functional metal-organic frameworks is of great interest due to their intriguing network topologies and their potential applications as microporous, magnetic or catalytically active species or in the fields of nonlinear optics, molecular separation, toxic materials adsorption and molecular sensors etc. (Batten & Robson, 1998;Burrows, 2011;Leininger et al., 2000;Tanabe & Cohen, 2011). Such molecular architectures have been successfully designed and synthesized by judicious combination of a metal 'node' and an organic ligands as 'spacer'. The roles of counter anions and different solvent molecules are also of significant effect on supramolecular self-assembly. More recently, the molecular geometry and flexibility of multidentate N-donor spacer ligands play key roles in the field of molecular materials and supramolecular self-assemble crystal engineering. For example, 4, 4'-bipyridine, 1, 2-bis(4-pyridyl)ethane and trans-bis(4-pyridyl)ethene as ligands can form a lot of coordination polymers with different structural features (Custelcean, 2010;Pschirer et al., 2002). The coordination polymer frameworks which were built by methylene C-bridged bipyridine, bitriazole and bisimidazole ligands have also been described widely (Hamilton & Ziegler, 2004;Jin et al., 2009) is a flexibie V-shaped N-donor ligand containing azo groups which is built up by two methylene C-bridged substituted imidazole rings. The title compound, [Ag(2-paBIM)SO 3 CF 3 ] n , (I), with a one-dimensional zigzag cationic chain structural motif was formed by the addition of a solution of 2-paBIM to AgSO 3 CF 3 .
Single crystal X-ray diffraction analysis reveals that complex (I) consists of one-dimensional cationic polymeric chains and uncoordinated CF 3 SO 3 -. The Ag + ions are coordinated by two imidazolyl unsubstituted nitrogen atoms of independent 2-paBIM ligands, which act as bridges between silver(I) centers (Fig.1). The Ag + ions show a coordination mode that is bent out of linearity with the bond angles of N-Ag-N being 153.9 (2)°. Ag-N bond lengths are 2.157 (5) Å and 2.170 (6) Å, respectively. Adjacent Ag······Ag distances in the same cationic chain are 8.841 (2) Å and the dihedral angle of the two 2-phenyldiazenyl-imidazole planes in the same ligand is 74.7 (3)°. Non-coordinated CF 3 SO 3 anions are filled in the voids of each zigzag cationic chain and show through the weak C-H······O hydrogen-bond interactions (Table 1).

Experimental
An CH 3 CN solution (5 ml) of 2-paBIM (178 mg, 0.5 mmol) was slowly diffused into an aqueous solution (5 ml) of AgSO 3 CF 3 (128 mg, 0.5 mmol) in a test tube. Red crystals of [Ag(2-paBIM)SO 3 CF 3 ] n were formed at the interface of solvent in two weeks and were obtained in 62% yield.

Refinement
The structure was refined as a racemic twin using TWIN and BASF keywords. H atoms were positioned geometrically at distances of 0.93 (CH), and 0.97 (CH 2 ) from the parent C atoms. A riding model was used during the refinement process.
The U iso values were constrained to be 1.2U eq of the corresponding carrier atom. Fig. 1. Structure of (I) showing the atom-numbering of one asymmetry unit. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity.