6-Chloro-1-methylindoline-2,3-dione

The title molecule, C9H6ClNO2, is essentially planar: the maximum deviation from the mean plane of the indoline ring is 0.020 (2) Å and the substituents do not deviate by more than 0.053 (2) Å from this plane. C—H⋯O hydrogen bonds help to consolidate the crystal structure.


Experimental
Crystal data

Structure Reports Online
The title molecule ( Fig. 1) is essentially planar with the maximum deviation of C4 atom from the mean-plane of indoline ring (N,C1-C8) is 0.020 (2) Å and the substituents do not deviate more than 0.053 (2) Å from this plane. In the crystal structure, intermolecular and intramolecular C-H···O hydrogen bonds helps to consolidate the crystal packing ( Fig. 2 & Tab. 1).
Experimental 6-Chloroisatin (1.81 g, 0.01 mol) was reacted with iodomethane (0.02 mol) in the presence of K 2 CO 3 (2.76 g, 0.02 mol) and tetrabutylammonium bromide (0.32 g, 0.001 mol) in DMF (60 ml). After 12 h stirring at room temperature, the precipitate was removed by filtration and purified by recrystallization from ethanol (m.p. 450-451 K; yield 67%). Yellow crystals of the title compound were obtained by slow evaporation from ethanol at room temperature.

Refinement
All H atoms were placed geometrically at the distances C-H = 0.93 and 0.96 Å for aryl and methyl type H-atoms and included in the refinement in riding motion approximation with U iso (H) = 1.2 or 1.5U eq (C). Fig. 1. The molecular structure of the title molecule showing the atom-numbering scheme and displacement ellipsoids at the 30% probability level.

Data collection
Enraf-Nonius CAD-4 diffractometer 1250 reflections with I > 2σ(I) 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 > σ(F 2 ) is used only for calculating Rfactors(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.