Experimental Crystal data

R factor = 0.057; wR factor = 0.181; data-to-parameter ratio = 16.9. In the title molecule, C21H18N2, the mean plane of the benzene ring of the mesityl group forms a dihedral angle of 82.69 (4) with that of the phenanthroline ring system. The crystal structure is stabilized by – stacking interactions between the phenanthroline system and the benzene ring of the mesityl group of a symmetry-related molecule, with centroid–centroid distances of 3.7776 (14) and 3.7155 (13) Å. Related literature For background information on phenanthroline derivatives, see: Schmittel et al. (2001); Garas & Vagg (2000). For infor-mation on phenanthroline ligands as used in coordination chemistry, see: Sauvage (1990). For the synthetic procedure