1-Allyl-1H-1,3-benzimidazol-2(3H)-one

The fused five- and six-membered rings in the title compound, C10H10N2O, are approximately coplanar, with an r.m.s. deviation of 0.008 Å. The mean plane of the allyl group is roughly perpendicular to the mean plane of the 1,3-benzimidazol-2(3H)-one system, making a dihedral angle of 86.1 (2)°. In the crystal, each molecule is linked to its symmetry equivalent partner by a pair of N—H⋯O and C—H⋯O hydrogen bonds.

The fused five-and six-membered rings in the title compound, C 10 H 10 N 2 O, are approximately coplanar, with an r.m.s. deviation of 0.008 Å . The mean plane of the allyl group is roughly perpendicular to the mean plane of the 1,3benzimidazol-2(3H)-one system, making a dihedral angle of 86.1 (2) . In the crystal, each molecule is linked to its symmetry equivalent partner by a pair of N-HÁ Á ÁO and C-HÁ Á ÁO hydrogen bonds.

D-HÁ
As a continuation of our research work devoted to the development of substituted benzimidazol-2-one derivatives (Belaziz et al., 2012;Ouzidan et al. 2011), we reported in this paper the synthesis of new benzimidazol-2-one derivative by action of allyl bromide with 1H-1,3-benzimidazol-2(3H)-one in the presence of a catalytic quantity of tetra-n-butylammonium bromide under mild conditions to furnish mono-substituted compound (Scheme 1).
The crystal structure of the 1-allyl-1H-1,3-benzimidazol-2(3H)-one molecule is built up from fused six-and fivemembered rings linked to C 3 H 5 chain as shown in Fg.1. The fused-ring system is essentially planar, with a maximum deviation of -0.010 (1) Å for C10. The allyl group is nearly perpendicular to the 1H-1,3-benzimidazol-2(3H)-one plane as indicated by the torsion angle of C8 C7 N1 C6 -70.44 (18)°. In the crystal, each molecule and its symmetry through the inversion center are linked by N2-H2···O1 and C3-H3···O1 hydrogen bonds in the way to form dimers as shown in

Figure 1
Molecular structure of the title compound with the atom-labelling scheme. Displacement ellipsoids are drawn at the 50% probability level. H atoms are represented as small circles.

Special details
Geometry. All s.u.'s (except the s.u. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell s.u.'s are taken into account individually in the estimation of s.u.'s in distances, angles and torsion angles; correlations between s.u.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell s.u.'s is used for estimating s.u.'s 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 > 2σ(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.