Dimethyl 2,2-bis(2-cyanoethyl)malonate

The asymmetric unit of the title compound, C11H14N2O4, contains one half-molecule; a twofold rotation axis passes through the central C atom. Intermolecular C—H⋯N hydrogen bonds link the molecules into a one-dimensional supramolecular structure.

The asymmetric unit of the title compound, C 11 H 14 N 2 O 4 , contains one half-molecule; a twofold rotation axis passes through the central C atom. Intermolecular C-HÁ Á ÁN hydrogen bonds link the molecules into a one-dimensional supramolecular structure.

Structure Reports Online
Many dicarbonyl compounds have been synthesized with "Michael Addition" method using diethy malonate as starting compound, but only a few "Michael Addition" diadducts were synthesized under normal condition (Zhang et al., 2004;Ranu & Banerjee, 2005). We are focusing our synthetic and structure studies on new products of "Michael Addition" diadducts from dicarbonyl compounds. We here report the crystal structure of the title compound (I).
The atom-numbering scheme of I is shown in Fig. 1, and all bond lengths and angles are within normal ranges (Allen et al., 1987). The asymmetric unit contains one half-molecule, and C4 lies on the twofold rotation axis vertical to ac plane, which generates the other half-molecule. An intermolecular C-H···N hydrogen bond (table and Fig. 2) helps to establish the 1-D supramolecular structure.
The resulting mixture was refluxed for 12 h, and 100 ml water was added to the mixture and the organic layer was dried with magnesium sulfate and vacuumed to removed the solvent. Then the crude compound I was obtained. It was crystallized from ethyl acetate (15 ml). Crystals of I suitable for X-ray diffraction were obtained by slow evaporation of an alcohol solution. 1 H NMR (CDCl 3 , δ, p.p.m.) 3.83 (s, 6H), 2.47 (t, 4H), 2.26 (t, 4H).

Refinement
All H atoms were positioned geometrically, with C-H = 0.96 and 0.97Å for methyl and methylene H atoms, and constrained to ride on their parent atoms, with U iso (H) = xU eq (C), where x = 1.5 for methyl H and x = 1.2 for methylene H atoms.  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 RR-factors based on ALL data will be even larger.
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )