(2,2′-Bipyrid­yl-κ²N,N′)bis­(η⁵-penta­methyl­cyclo­penta­dien­yl)barium

In the title compound, [Ba(C₁₀H₁₅)₂(C₁₀H₈N₂)], the Ba—N distances are 2.798 (3) and 2.886 (3) Å, and the Cp ring centroid distances to Ba²⁺ are 2.7291 (7) and 2.7192 (9) Å. The angle between the N atoms in the bypyridine ligand and the metal ion is 56.80 (8)° and the N—C—C—N torsion angle in the bi­pyridine ligand is 1.7 (4)°. The bi­pyridine ligand is almost planar, the dihedral angle formed by the intersection of the planes defined by the pyridyl rings being 3.04 (19)°, and the angle between the plane defined by the Ba²⁺ ion and the two bipyridyl N atoms and the plane defined by the 12 atoms of the bi­pyridine ligand is 10.2 (3)°. The average Ba—N and Ba—centroid distances are 0.16 and 0.14 Å longer, respectively, than the equivalent distances in the isotypic strontium compound [Kazhdan et al. (2008). Acta Cryst. E64, m1134]. This difference is in accord with the difference between the ionic radii of 0.16 Å suggested by Shannon [Acta Cryst. (1976), A32, 751–767].

5,6-Dimeth­yl-1,10-phenanthroline

In the title compound, C₁₄H₁₂N₂, the N...N distance is 2.719 (1) Å. The N—C—C—N torsion angle [0.9 (1)°] is close to the ideal value of 0° as expected. Bond lengths and angles are consistent with those observed for [1,10]phenanthroline and coordinated 5,6 dimeth­yl[1,10]phenanthroline. In the crystal, C—H...N hydrogen bonds link the mol­ecules into C(4) chains running parallel to the b axis. Weak π–π inter­actions between benzene and pyridine rings [centroid–centroid distance = 3.5337 (7) Å] and between benzene rings [centroid–centroid distances = 3.6627 (7) and 3.8391 (7)Å] also occur.