Crystal structure of chlorido(2-{1-[2-(4-chlorophenyl)hydrazin-1-ylidene-κN]ethyl}pyridine-κN)(η5-pentamethylcyclopentadienyl)rhodium(III) chloride

The title compound, [Rh(η5-C5Me5)Cl(C13H12ClN3)]Cl, is chiral at the metal and crystallizes as a racemate. Upon coordination, the hydrazinylidenepyridine ligand is non-planar, an angle of 54.42 (7)° being observed between the pyridine ring and the aromatic ring of the [2-(4-chlorophenyl)hydrazin-1-ylidene]ethyl group.

The cation of the title compound, [Rh( 5 -C 5 Me 5 )Cl(C 13 H 12 ClN 3 )]Cl, adopts a typical piano-stool geometry. The complex is chiral at the metal and crystallizes as a racemate. Upon coordination, the hydrazinylidenepyridine ligand is nonplanar, an angle of 54.42 (7) being observed between the pyridine ring and the aromatic ring of the [2-(4-chlorophenyl)hydrazin-1-ylidene]ethyl group. In the crystal, a weak interionic N-HÁ Á ÁCl hydrogen bond is observed.

Structural commentary
The molecular structure of the title compound is presented in Fig. 1. The cationic complex adopts a typical piano-stool geometry and it is chiral at the metal centre. The salt crystallizes as a racemate in the orthorhombic space group Pbca. In the complex, the hydrazinylidenepyridine ligand is N,Ncoordinating, the N-hydrazono and the N-pyridine groups ISSN 2056-9890 forming with the rhodium(III) atom a five-membered metallacycle. Upon coordination, the hydrazinylidenepyridine ligand is non-planar, an angle of 54.42 (7) being observed between the planes of pyridine and the benzene ring of the [(4-chlorophenyl)hydrazono]ethyl group. Otherwise, all geometrical data around the rhodium(III) atom are similar to those found in analogous N,N-chelated pentamethylcyclopentadienyl rhodium complexes (Gupta et al., 2011;Payne et al., 2013).

Supramolecular features
The N-H group of the hydrazinylidenepyridine ligand interacts weakly with the counter-anion giving rise to a nearly linear hydrogen bond (Table 1). No significant C-HÁ Á Á or stacking interactions are observed.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. Except for the N-bound H atom, which was refined freely, all hydrogen atoms were included in calculated positions and treated as riding atoms using SHELXL97 default parameters, with C-H = 0.93 Å for C arom and 0.96 Å for CH 3 , and with U iso (H) = 1.2 U eq (C) or 1.5 U eq (C) for methyl H atoms. Table 1 Hydrogen-bond geometry (Å , ).

Figure 1
The molecular structure of the title compound, with displacement ellipsoids drawn at the 50% probability level.   , 2000); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-32 (Farrugia, 2012); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008). Kα graphite monochromated radiation. Image plate distance 100 mm, φ oscillation scans 0 -180°, step Δφ = 0.8°, 5 minutes per frame. 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.