2-Phenyl-4,5-di-2-pyridyl-1H-imidazole

In the title compound, C19H14N4, which was crystallized from dimethyl sulfoxide, the arene and heterocyclic rings of the lophine analogue framework differ only slightly from coplanarity (dihedral angles range from 8.8 to 20.2°), and intramolecular N—H⋯N and C—H⋯N interactions help to establish the conformation. The crystal packing features a number of weak C—H⋯N, N—H⋯N hydrogen-bond type contacts, and C—H⋯π interactions, leading to the formation of a herringbone structure.


Comment
In the title compound ( Fig.1), the imidazole and the phenyl ring are nearly coplanar with a dihedral angle of 8.87 (9)° while the two pyridine rings are tilted showing dihedral angels of 11.14 (8) and 20.17 (8)° with respect to the imidazole unit. As compared with related imidazoles having phenyl substituents in 4-and 5-position (Kaftory et al., 1998;Benisvy et al., 2003;Martinez et al., 2004;Seethalakshmi et al., 2006 andThiruvalluvar et al., 2007), the dihedral angels involving pyridine rings and imidazole of the present compound are decreased in value of about 20°. This is presumably attributed to the CH for N exchange being connected with the phenyl for pyridyl substitution, which lowers torsional strain between the two planes defining the dihedral angels.
As a consequence of the almost planar overall molecular conformation, weak intramolecular hydrogen bonding contacts (Desiraju & Steiner, 1999) involving the donator and acceptor atoms N1 and N3 as well as C5 and N4, respectively, are rather probable to exist (Table 1).
Due to steric shielding of the nitrogen atoms, strong hydrogen bonds are also absent in the crystal packing. Thus, the nitrogen atoms N3 and N4 of the pyridine rings are acting as hydrogen acceptors and the imidazole nitrogen N1 as a hydrogen donator only in the formation of weak intermolecular C-H···N and N-H···N type contacts (Desiraju & Steiner, 1999) (Table 1). Furthermore the crystal packing is stabilized by weak C-H···π interactions (Table 1)

Experimental
The title compound was synthesized from benzaldehyde, 1,2-dipyridin-2-yl-ethane-1,2-dione and ammonium acetate following the literature procedure (K. Nakashima et al., 1998). Yellow prisms suitable for X-ray diffraction were obtained by evaporation of a the solvent from a solution of the title compound in DMSO.

Refinement
H atoms, except for H1, were positioned geometrically and allowed to ride on their parent atoms, with C-H = 0.95 Å, and U iso = 1.2-1.5 U eq (parent atom).
supplementary materials sup-2 Figures   Fig. 1. A view of the molecular structure of the title compound, showing 50% probability displacement ellipsoids for the non-hydrogen atoms.