6,7-Dihydro-3H-1,4-diazepino[1,2,3,4-lmn][1,10]phenanthroline-3,9(5H)-dione

In the title compound, C15H12N2O2, the seven-membered ring bearing the three methylene C atoms displays a puckered conformation, with the methylene C atoms deviating from the plane of the benzene ring by 0.05 (1), 0.98 (1) and 1.04 (1) Å. The phenanthroline unit is not planar; the dihedral angles between this benzene ring and the other pyridyl rings are 9.62 (4) and 9.31 (4)°. The crystal packing is stabilized by π–π interactions between two phenanthroline ring systems, forming a centrosymmetric dimer with a centroid–centroid distance of 3.656 (1) Å.

In the title compound, C 15 H 12 N 2 O 2 , the seven-membered ring bearing the three methylene C atoms displays a puckered conformation, with the methylene C atoms deviating from the plane of the benzene ring by 0.05 (1), 0.98 (1) and 1.04 (1) Å . The phenanthroline unit is not planar; the dihedral angles between this benzene ring and the other pyridyl rings are 9.62 (4) and 9.31 (4) . The crystal packing is stabilized byinteractions between two phenanthroline ring systems, forming a centrosymmetric dimer with a centroid-centroid distance of 3.656 (1) Å .

Related literature
For background tointeractions in supramolecular chemistry, see: Sisson et al. (2006). For a related structure, see: Nadeem et al. (2009

Comment
In supramolecular chemistry it is well establish that the self-association of individual molecules can lead to the formation of highly complex and fascinating supramolecular assemblies if π-π interactions contribute to the formation of specific motifs (Sisson et al., 2006). As a part of our ongoing investigation on the nature of π-π (Nadeem et al., 2009) stacking and supramolecular chemistry, the title compound ( Figure-1), has been prepared and its crystal structure is reported here. The crystal packing is stabilized by π-π interactions between two phenanthroline ring systems forming a centrosymmetric dimer with a centroid···centroid distance of 3.656 (1) Å. A typical double bond distance 1.236 (2) Å was observed for C1-O1 C8-O2 while a characteristic single bond distances 1.386 (1) Å and 1.393 (1) Å were observed for C1-N1 and C8-N2 respectively.

Refinement
The H atoms were geometrically placed and treated as riding atoms with C-H = 0.96 Å, and U iso (H) = 1.2 U eq (parent C-atom). Fig. 1. Molecular Structure of (I) with atom labels and 50% probability displacement ellipsoids.

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 supplementary materials sup-3 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.
Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > 2sigma(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.