Aquabis(2,2′-bipyridine-κ2 N,N′)(isonicotinamide-κN)ruthenium(II) bis(trifluoromethanesulfonate)

In the crystal structure of the title compound, the ruthenium(II) metal center is surrounded by two bidentate 2,2′-bipyridine, an isonicotinamide ligand, and a water in a distorted octahedral geometry. Hydrogen bonding is present between counter-ion and ligand.


Structure description
Over the last three years, a lot of effort has been directed into studying ruthenium(II) bis(bipyridine) complexes due to their catalytic properties (Griffin et al., 2021), luminescence (Cue ´llar et al., 2021) and biological activity (Al-Wahaib et al., 2021;Allison et al., 2021).Last year, bipyridine ruthenium(II) complexes with halogen-substituted salicylates showed promising in vitro antiproliferative activity against MCF-7 (breast cancer) and U-118 MG (human glioma) cell lines (Schoeller et al., 2023).Our research group's interest currently lies in synthesizing metal complexes with application as antiproliferative agents; as part of our research in this area, we describe the synthesis and structure of the title ruthenium(II) complex, Fig. 1.
The asymmetric unit contains the title compound, with four symmetry-related entities inside the unit cell.The ruthenium(II) ion shows a distorted octahedral coordination environment defined by two 2,2 0 -bipyridine ligands, one isonicotinamide ligand and a water molecule.Trifluoromethanesulfonate ions sit in the outer coordination sphere, balancing the charge of the metal complex.All the Ru-N bond bond lengths are in good agreement with comparable ruthenium(II) bis(2,2 0 -bipyridine) complexes currently available in the Cambridge Structural Database (CSD, version 5.45, Nov 2023; Groom et al., 2016;Huang & Ogawa, 2006, refcode LECFOP;Keniley Jr et al., 2013, refcode AROJIB01;Yoshikawa et al., 2016, refcode DACBER;de Souza et al., 2017, refcode TAWQOA), The N-Ru-N angles found in the bipyridine ligands also concur with the values reported in the previously referenced ruthenium(II) bipyridine complexes.The Ru-O bond length matches well with the distance in other ruthenium complexes with a coordinating water molecule (Gupta et al., 1992, refcode KUPBUS;Bonnet et al., 2003, refcode IPESIF;Ghaderian et al., 2020, refcode LAGCIJ).All relevant bonds and angles are presented in Table 1.
The packing diagram reveals the stacking of the asymmetric units in columns observable when looking at the crystal parallel to the caxis (Fig. 2).Contiguous pyridine rings show weak �-� stacking interactions, with a centroid-to-centroid distance (Cg� � �Cg) of 3.791 (4) A ˚and an offset distance of 1.559 A ˚, which are responsible for the stacking into columns.Trifluoromethanesulfonate ions sit in the gap between columns and are held in place by hydrogen bonds between one of the oxygen atoms of the trifluoromethanesulfonate ion and one of the hydrogen atoms in the water molecule, as well as between the oxygen in the isonicotinamide ligand and the second hydrogen in the water molecule (Table 2).

Synthesis and crystallization
The title compound was synthesized by the reaction of cis-Ru(bpy) 2 Cl 2 (0.100 g, 0.206 mmol) with Ag(CF 3 SO 3 ) (0.106 g, 0.412 mmol) in 50 ml of EtOH.After heating and stirring for about 1 h at 323.15 K, the solution was filtrated using a PTFE syringe filter to remove AgCl.Isonicotinamide (0.050 g, 0.41 mmol) was then added to the mixture and the resulting solution was heated at 338.15 K until the volume was reduced to about 10 ml.Crystal suitable for X-ray diffraction were grown by vapor diffusion of diethyl ether over a saturated acetonitrile solution of the title complex.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 3.One of the trifluoromethanesulfonate ions has four atoms disordered over two sets of sites.The site occupation factors of the disordered atoms were set to 0.85 and 0.15, respectively.The displacement parameters of the minor occupied sites were restrained to an isotropic behavior.The C-S distance of the minor occupied sites was restrained to 1.70 (2) A ˚. H atoms were refined using a riding model with C-H = 0.95 A ˚and U iso (H) = 1.2U eq (C) or O-H = 0.89 A ˚and U iso (H) = 1.5U eq (O).

Figure 1
Asymmetric unit of the title compound with displacement ellipsoids drawn at the 50% probability level; hydrogen bonds shown as dashed lines.The minor occupied sites of the disordered trifluoromethanesulfonate ion are omitted for clarity.

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.

Figure 2
Figure 2Perspective view of the crystal packing of the title complex parallel to the c axis; H atoms and the minor occupied sites of the disordered trifluoromethanesulfonate ion are omitted for clarity.

Table 3
Experimental details.