3-Phenylpyridinium tetrachloridoaurate(III)

In the title molecular salt, (C11H10N)[AuCl4], the AuIII atom adopts an almost regular square-planar coordination geometry and the dihedral angle between the aromatic rings of the 3-phenylpyridinium cation is 23.1 (3)°. In the crystal, the ions interact by way of N—H⋯Cl and C—H⋯Cl hydrogen bonds.

In the title molecular salt, (C 11 H 10 N) [AuCl 4 ], the Au III atom adopts an almost regular square-planar coordination geometry and the dihedral angle between the aromatic rings of the 3-phenylpyridinium cation is 23.1 (3) . In the crystal, the ions interact by way of N-HÁ Á ÁCl and C-HÁ Á ÁCl hydrogen bonds.
The molecule of the title compound, (I), (Fig. 1), contains one independent protonated 3-phenylpyridinium cation and one [AuCl 4 ]anion. The Au III atom has a squareplanar environment defined by four Cl atoms. In [AuCl 4 ]anion, the Au-Cl bond lengths and angles (Table 1) are within normal range (II, III, VII, VIII and IX).
In the crystal structure, intermolecular N-H···Cl and C-H···Cl hydrogen bonds (Table 2) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure.

Experimental
A solution of 3-phenylpyridine (0.11 g, 0.09 ml, 0.74 mmol) in methanol (5 ml) was added to a solution of HAuCl 4 .3H 2 O, (0.29 g, 0.74 mmol) in acetonitrile (15 ml) and the resulting yellow solution was stirred for 30 min at 313 K. Then, it was left to evaporate slowly at room temperature. After five days, yellow blocks of (I) were isolated (yield 0.26 g; 71.0%).

Refinement
All H atoms were positioned geometrically, with C-H=0.93Å for aromatics H and constrained to ride on their parent atoms, with U iso (H)=1.2U eq . supplementary materials sup-2 Figures   Fig. 1. The molecular structure of (I). Displacement ellipsoids are drawn at the 40% probability level.

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.
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 Rfactors(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.