(2,2′-Bipyridyl)(η6-p-cymene)iodidoruthenium(II) hexafluoridophosphate

The title compound crystallizes in the triclinic P (Z = 2) space group as a half-sandwich complex resembling a three-legged piano stool. The crystal packing features C—H⋯F/I interactions.


Structure description
6 -Arene-ruthenium(II) complexes have demonstrated a high tendency to exhibit antitumour activity through DNA binding interactions (Colina-Vegas et al., 2015;Yarahmadi et al., 2023) and protein kinase inhibition (Atilla-Gokcumen et al., 2006). In addition, they also exhibit catalytic properties, especially in the hydrogenation of ketones (Ngo & Do, 2020). The investigation of their structural properties will provide insight into the strategic design and development of new similar ruthenium half-sandwich complexes.
The title compound (Fig. 1) shows the typical piano-stool conformation with the pcymene unit displaced by 1.6902 (17) Å from the central Ru II atom, and the bipyridyl and iodido ligands taking up the remainder of the coordination sphere. The bond lengths of Ru-N1 [2.073 (3) Å ] and Ru-N2 [2.072 (3) Å ] are identical within experimental error, but were found to be slightly shorter than normal (CSD V5.43 September 2022 update, 785 entries with p-cymene-Ru-N,N 0 bidentate; Groom et al., 2016) in 1501 samples with a mean value of 2.11 (4) Å . The coordination environment is distorted from the ideal octahedral shape, primarily due to the pincer movement and twisting of the bidentate data reports  , dihedral angle between the two pyridyl moieties of the bipyridyl ligand = 5.9 (2) ]. The isopropyl group is eclipsed with the iodido group, similar to what is observed for the chlorido counterpart, reported as a non-solvated (Colina-Vegas et al., 2015) and a methanol solvated form (Wu et al., 2008), although the three crystal structures are not isostructural. A superimposed drawing of the iodido and chlorido complexes shows marginal deviations with the 2,2-bypiridyl and methyl group of the cymene ligand, resulting in an overall r.s.m.d. of 0.215 and 0.175 Å for the non-solvated (Colina-Vegas et al., 2015) and methanolsolvated chlorido analogues (Wu et al., 2008), respectively (see Fig. 2). The overlay is based on all non-hydrogen atoms except for the halogen atoms.
Several non-classical hydrogen bonds exist between a C-H group (from the Ru complex) and the F atom of the PF 6 anion, as well as one to an I atom of a neighbouring molecule ( Fig. 3 and Table 1). No discernible packing motifs were observed.

Synthesis and crystallization
To a solution of (p-cymene)diiodido ruthenium(II) dimer (200 mg, 0.20 mmol, 1 eq.) in methanol was added bipyridine (127 mg, 0.82 mmol, 4 eq.), resulting in the formation of an orange precipitate within 2 min. The reaction mixture was refluxed for 6 h, after which it was cooled to room temperature. NH 4 PF 6 (100 mg, 0.61 mmol, 3 eq) was added and stirred for 1 h, and then concentrated in vacuo. The residue was purified by column chromatography using silica gel and the solvent system, CH 2 Cl 2 : MeOH = 99:1 (R f = 0.36), as eluent to obtain an orange compound (108 mg, 0.20 mmol).  An overlay displaying the geometrical alignment between the title compound (in red) with the non-solvated chlorido analogue (Colina-Vegas et al., 2015, in blue), and the methanol-solvated chlorido analogue (Wu et al., 2008, in green) with r.m.s.d.s of 0.215 and 0.175 Å , respectively.

Figure 1
The molecular entities of the title compound with 50% probability displacement ellipsoids with and without the second component of the PF 6 À disorder (hydrogen atoms are omitted for clarity).

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 2. The PF 6 counter-ion had elongated thermal displacement ellipsoids and was treated using a twofold disorder model. Refinement of the disorder was kept stable with SADI distance restraints and ellipsoid sizes by SIMU with e.s.d.'s of 0.02 Å and 0.02 Å 2 , respectively. The distribution of the disorder model over the two sites was coupled to a free variable that will refine to unity for the two components. The final ratio was 65.0 (8):35.0 (8) for parts A:B.

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.

data-2
IUCrData (2023). 8, x230392 Refinement. The hydrogen atoms were refined isotropically in their idealized geometrical positions while riding on their anisotropic parent atoms with U iso = 1.2U eq for the aromatic and methine protons, and U iso = 1.5U eq for the methyl protons, the latter was refined as a fixed rotor and adjusted to match the hydrogen atoms electron density from the Fourier difference map. The highest electron density of 0.51 e Å -3 is 1.17 Å away from F2A, while the deepest electron density of -0.67 e Å -3 is 0.76 Å away from I.

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