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.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.065
• wR factor = 0.155
• Data-to-parameter ratio = 14.0

checkCIF/PLATON results

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Alert level C
PLAT764_ALERT_4_C Overcomplete CIF Bond List Detected (Rep/Expd) .       1.11 Ratio

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   1 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   0 ALERT type 2 Indicator that the structure model may be wrong or deficient
   0 ALERT type 3 Indicator that the structure quality may be low
   1 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

Dicarbonyl compounds represent an important class of starting materials to increase the carbon number of organic compounds (Kim et al., 2001). Some dicarbonyl compounds are useful for the synthesis of enantiomerically pure alcohols (Chetia et al., 2004).

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.

Related literature

For general background, see: Kim et al. (2001); Chetia et al. (2004); Zhang et al. (2004); Ranu & Banerjee (2005). For bond–length data, see: Allen et al. (1987).

S2. Experimental

Dimethyl malonate (50 mmol) was dissolves in n–hexane (20 ml), then anhydrous potassium carbonate (100 mmol) and tetrabutylammonium bromide (1 g) was added. Finally acrylonitrile (100 mmol) was slowly dropped to the solution above. 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. ¹H NMR (CDCl₃, δ, p.p.m.) 3.83 (s, 6H), 2.47 (t, 4H), 2.26 (t, 4H).

S3. 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.

Computing details

Data collection: CAD-4 Software (Enraf–Nonius, 1989); cell refinement: CAD-4 Software (Enraf–Nonius, 1989); data reduction: XCAD4 (Harms & Wocadlo, 1995); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: SHELXTL (Sheldrick, 2008); software used to prepare material for publication: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. A view of the molecular structure of I showing the atom–numbering scheme. Displacement ellipsoids are drawn at 30% probability level. H atoms are presented as a spheres of arbitrary radius.
	Fig. 2. The 1–D supramolecular structure developed by C—H···N hydrogen bonds (dashed lines) [Symmetry codes: (i) -x, 2 - y, 1 - z].

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

Crystal data

C11H14N2O4	F(000) = 504
Mr = 238.24	Dx = 1.304 Mg m^−3
Monoclinic, C2/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -C 2yc	Cell parameters from 25 reflections
a = 13.071 (3) Å	θ = 10–14°
b = 8.5060 (17) Å	µ = 0.10 mm^−1
c = 10.914 (2) Å	T = 293 K
β = 90.55 (3)°	Block, colourless
V = 1213.4 (4) Å^3	0.40 × 0.30 × 0.20 mm
Z = 4

Data collection

Enraf–Nonius CAD-4 diffractometer	860 reflections with I > 2σ(I)
Radiation source: Fine–focus sealed tube	Rint = 0.048
Graphite monochromator	θmax = 25.2°, θmin = 2.9°
ω/2θ scans	h = −15→15
Absorption correction: ψ scan (North et al., 1968)	k = 0→10
Tmin = 0.961, Tmax = 0.975	l = 0→12
1140 measured reflections	3 standard reflections every 200 reflections
1091 independent reflections	intensity decay: none

Refinement

Refinement on F^2	Primary atom site location: Direct
Least-squares matrix: Full	Secondary atom site location: Difmap
R[F^2 > 2σ(F^2)] = 0.065	Hydrogen site location: Geom
wR(F^2) = 0.155	H-atom parameters constrained
S = 0.99	w = 1/[σ^2(Fo^2) + (0.0591P)^2 + 3.2284P] where P = (Fo^2 + 2Fc^2)/3
1091 reflections	(Δ/σ)max < 0.001
78 parameters	Δρmax = 0.21 e Å^−3
0 restraints	Δρmin = −0.24 e Å^−3

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 F² against ALL reflections. The weighted R–factor wR and goodness of fit S are based on F², conventional R–factors R are based on F, with F set to zero for negative F². The threshold expression of F² > 2σ(F²) is used only for calculating R–factors(gt) etc. and is not relevant to the choice of reflections for refinement. R–factors based on F² 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 (Ų)

	x	y	z	Uiso*/Ueq
N1	−0.1143 (3)	0.5595 (3)	0.4119 (3)	0.0730 (10)
C1	−0.1098 (2)	0.6248 (3)	0.5039 (3)	0.0471 (7)
O1	0.15852 (15)	1.0070 (2)	0.6705 (2)	0.0516 (6)
O2	0.09191 (13)	1.1101 (2)	0.84034 (16)	0.0402 (5)
C2	−0.1041 (3)	0.7072 (4)	0.6228 (3)	0.0589 (9)
H2A	−0.1056	0.6311	0.6890	0.071*
H2B	−0.1628	0.7760	0.6312	0.071*
C3	−0.00519 (19)	0.8043 (3)	0.6315 (2)	0.0333 (6)
H3A	−0.0013	0.8737	0.5612	0.040*
H3B	0.0532	0.7340	0.6293	0.040*
C4	0.0000	0.9032 (4)	0.7500	0.0301 (8)
C5	0.09365 (19)	1.0115 (3)	0.7444 (2)	0.0309 (6)
C6	0.1753 (2)	1.2212 (4)	0.8494 (3)	0.0481 (8)
H6A	0.1667	1.2853	0.9209	0.072*
H6B	0.1756	1.2867	0.7778	0.072*
H6C	0.2390	1.1653	0.8555	0.072*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0893 (16)	0.0651 (16)	0.0628 (19)	0.0048 (16)	−0.0436 (17)	−0.0172 (15)
C1	0.0547 (18)	0.0469 (14)	0.0532 (17)	−0.0015 (14)	−0.0192 (13)	−0.0050 (14)
O1	0.0430 (12)	0.0432 (12)	0.0585 (14)	−0.0076 (9)	0.0028 (10)	−0.0102 (10)
O2	0.0498 (10)	0.0442 (10)	0.0465 (11)	−0.0111 (8)	−0.0098 (8)	−0.0088 (8)
C2	0.0571 (18)	0.0484 (17)	0.0582 (13)	−0.0162 (16)	−0.0205 (16)	−0.0162 (15)
C3	0.0404 (14)	0.0479 (12)	0.0355 (13)	0.0018 (11)	−0.0067 (10)	−0.0007 (10)
C4	0.0476 (19)	0.0472 (16)	0.0355 (18)	−0.0017 (10)	−0.0025 (14)	0.0006 (10)
C5	0.0421 (13)	0.0469 (13)	0.0344 (13)	0.0058 (10)	−0.0093 (10)	0.0032 (10)
C6	0.0477 (17)	0.0452 (16)	0.0549 (18)	−0.0162 (14)	−0.0138 (13)	−0.0046 (13)

Geometric parameters (Å, º)

N1—C1	1.149 (4)	C3—H3A	0.9700
C1—C2	1.476 (4)	C3—H3B	0.9700
O1—C5	1.177 (3)	C4—C5	1.534 (3)
O2—C5	1.341 (3)	C4—C5^i	1.534 (3)
O2—C6	1.445 (3)	C4—C3^i	1.544 (3)
C2—C3	1.537 (4)	C6—H6A	0.9600
C2—H2A	0.9700	C6—H6B	0.9600
C2—H2B	0.9700	C6—H6C	0.9600
C3—C4	1.544 (3)
N1—C1—C2	179.4 (4)	C5—C4—C3	108.85 (13)
C5—O2—C6	116.3 (2)	C5^i—C4—C3	109.39 (13)
C1—C2—C3	110.1 (3)	C5—C4—C3^i	109.39 (13)
C1—C2—H2A	109.6	C5^i—C4—C3^i	108.85 (13)
C3—C2—H2A	109.6	C3—C4—C3^i	113.9 (3)
C1—C2—H2B	109.6	O1—C5—O2	125.0 (2)
C3—C2—H2B	109.6	O1—C5—C4	126.0 (2)
H2A—C2—H2B	108.1	O2—C5—C4	108.96 (19)
C2—C3—C4	112.0 (2)	O2—C6—H6A	109.5
C2—C3—H3A	109.2	O2—C6—H6B	109.5
C4—C3—H3A	109.2	H6A—C6—H6B	109.5
C2—C3—H3B	109.2	O2—C6—H6C	109.5
C4—C3—H3B	109.2	H6A—C6—H6C	109.5
H3A—C3—H3B	107.9	H6B—C6—H6C	109.5
C5—C4—C5^i	106.2 (3)
C1—C2—C3—C4	175.4 (2)	C5^i—C4—C5—O1	−126.7 (3)
C2—C3—C4—C5	−173.0 (2)	C3—C4—C5—O1	−9.0 (3)
C2—C3—C4—C5^i	−57.4 (3)	C3^i—C4—C5—O1	116.0 (3)
C2—C3—C4—C3^i	64.63 (19)	C5^i—C4—C5—O2	55.37 (14)
C6—O2—C5—O1	2.0 (4)	C3—C4—C5—O2	173.02 (18)
C6—O2—C5—C4	180.0 (2)	C3^i—C4—C5—O2	−61.9 (2)

Symmetry code: (i) −x, y, −z+3/2.

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
C6—H6B···N1^ii	0.96	2.57	3.494 (5)	161

Symmetry code: (ii) −x, −y+2, −z+1.