μ-2,3,5,6-Tetra­kis(pyridin-2-yl)pyrazine-bis­[(2,2′:6′,2′′-terpyridine)­ruthenium(II)] tetra­kis­(hexa­fluoridophosphate) acetonitrile tetra­solvate

In the title compound [Ru₂(C₁₅H₁₁N₃)₂(C₂₄H₁₆N₆)](PF₆)₄·4CH₃CN, two of the counter-ions and one of the solvent mol­ecules are disordered with occupancies for the major components between 0.57 (2) and 0.64 (1). The structure of the dinuclear tetracation exhibits significant distortion from planarity in the bridging 2,3,5,6-tetra­kis­(pyridin-2-yl)pyrazine (tppz) ligand, which has a saddle-like geometry with an average dihedral angle of 42.96 (18)° between adjacent pyridine rings. The metal–ligand coordination environment is nearly equivalent for the two Ru^II atoms, which have a distorted octa­hedral geometry due to the restricted bite angle [157.57 (13)–159.28 (12)°] of their two mer-arranged tridendate ligands [2,2′:6′,2′′-terpyridine (tpy) and tppz] orthogonal to each other. At the peripheral tpy ligands, the average Ru—N bond distance is 2.072 (4) Å for the outer N atoms trans to each other (N_outer) and 1.984 (1) Å for the central N atoms (N_central). At the bridging tppz ligand, the average metal–ligand distances are significantly shorter [2.058 (4) Å for Ru—N_outer and 1.965 (1) Å for Ru—N_central] as a result of both the geometric constraints and the stronger π-acceptor ability of the pyrazine-centered bridge. The dihedral angle between the two tpy planes is 27.11 (6)°. The intra­molecular linear distance between the two Ru atoms is 6.6102 (7) Å.