Tetra-μ-acetato-κ8 O:O′-bis[(3-chloropyridine-κN)ruthenium(II,III)](Ru—Ru) hexafluoridophosphate 1,2-dichloroethane monosolvate

The mixed-valent cationic complex of the solvated title salt, [Ru2(μ-O2CCH3)4(C5H4ClN)2]PF6·C2H4Cl2, exhibits a classic paddlewheel or lantern structure with each Ru atom in a slightly distorted octahedral environment.


Structure description
Earlier research in our lab dealt with the chemistry of various mixed-valent diruthenium(II,III) tetraacetate complexes incorporating substituted pyridines and other, biologically relevant, heterocyclic N-donors in the axial coordination positions (Bland et al., 2005;Gilfoy et al., 2001;Minaker et al., 2011;Vamvounis et al., 2000). At that time we were unable to obtain structures of amino-or chloro-pyridine diadducts. Recently, we have been able to characterize both a 3-aminopyridine diadduct (Aquino et al., 2021) and the 3-chloropyridine diadduct is reported here. This is the first crystal structure of a chloro-pyridine diadduct of a diruthenium(II,III) tetracarboxylate that we are aware of.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1. Two reflections were removed from the refinement because of poor agreements between F 2 (obs) and F 2 (calc), 775 and 826. In the cation, the methyl groups of the acetate ligands were modeled in the refinement as idealized disordered methyl groups with the two sets of positions rotated from each other by 60 . The crystal structure was found to contain solvent molecules. The recrystallization solvents were dichloroethane and diethyl ether. The SQUEEZE routine (Spek, 2015) in PLATON (Spek, 2020) was used to get an estimate of the void volumes and of the unaccounted electron density in them. The unit cell was found to contain one void of 228 Å 3 with 50 electrons per void. This suggested that there was one molecule of dichloroethane in each void and it was modeled as such. The disorder in the solvent was modeled by two equally occupied parts, which were then also split again across an inversion center, giving all  Computer programs: CrystalStructure (Rigaku, 2007), SIR2004 (Burla et al., 2005), SHELXL (Sheldrick, 2015), Merdury (Macrae et al., 2020) and publCIF (Westrip, 2010).

Figure 1
The molecular structure of the title compound with displacement ellipsoids at the 50% probability level. Unlabeled atoms are generated by the symmetry operations (i) (Àx + 1, Ày, Àz) and (ii) (Àx + 2, Ày, Àz + 1). Only one orientation of the disordered methyl groups and the disordered C 2 H 4 Cl 2 solvent molecule is shown atoms an occupancy of 0.25. The geometries of all the parts were restrained to be similar. In addition the C-C and the C-Cl bond lengths were restrained to reasonable values. The heavy atoms of the same type in the solvent were restrained to have similar displacement parameters and the carbon atoms were restrained to have more isotropic ellipsoids. Finally, rigid-bond restraints were placed over each solvent part.

Funding information
Funding for this research was provided by: Natural Sciences and Engineering Research Council of Canada (grant to Manuel A.S. Aquino).

data-1
IUCrData ( 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.