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The crystal structure of N,N′-methylenebisacrylamide was determined through the geometry optimization of the molecular unit with density functional theory and conformational analysis, and then through the calculation of the packing via a crystal structure prediction protocol, based on lattice energy minimization. All the calculated structures were ranked, comparing their powder pattern with the laboratory low-quality X-ray diffraction data. Rietveld refinement of the best three proposed structures allowed the most probable crystal arrangement of the molecules to be obtained. This approach was essential for disentangling the twinning problems affecting the single-crystal X-ray diffraction data, collected on samples obtained via recrystallization of powder, which definitely confirmed the predicted model. It was found that N,N′-methylenebisacrylamide shows a monoclinic structure in the space group C2/c, with lattice parameters a = 17.822 (12), b = 4.850 (3), c = 19.783 (14) Å, β = 102.370 (9)°, V = 1670 (2) Å3. Two strong interactions between the amide protons and the carbonyl groups of neighbouring molecules were found along the b axis, determining the crystal growth in the form of wires in this direction. This work provides a further example of how computational methods may help to investigate low-quality molecular crystals with standard diffraction techniques.
Supporting information
CCDC references: 1013040; 1051528
Data collection: APEX2 (Bruker, 2008); cell refinement: APEX2 (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 1990); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997); molecular graphics: ORTEP-3 for Windows (Farrugia, 1997); software used to prepare material for publication: WinGX (Farrugia, 1999).
Crystal data top
C7H10N2O2 | F(000) = 656 |
Mr = 154.17 | Dx = 1.226 Mg m−3 |
Monoclinic, C2/c | Mo Kα radiation, λ = 0.71073 Å |
a = 17.822 (12) Å | Cell parameters from 90 reflections |
b = 4.850 (3) Å | θ = 5–15° |
c = 19.783 (14) Å | µ = 0.09 mm−1 |
β = 102.370 (9)° | T = 293 K |
V = 1670 (2) Å3 | Needle, colorless |
Z = 8 | 0.20 × 0.09 × 0.06 mm |
Data collection top
APEX II diffractometer | 1461 independent reflections |
Radiation source: fine-focus sealed tube | 871 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.075 |
OMEGA SCAN scans | θmax = 25.0°, θmin = 2.1° |
Absorption correction: empirical (using intensity measurements) software bruker | h = −21→21 |
Tmin = 0.552, Tmax = 0.746 | k = −5→5 |
8010 measured reflections | l = −23→23 |
Refinement top
Refinement on F2 | Primary atom site location: structure-invariant direct methods |
Least-squares matrix: full | Secondary atom site location: difference Fourier map |
R[F2 > 2σ(F2)] = 0.074 | Hydrogen site location: inferred from neighbouring sites |
wR(F2) = 0.228 | H-atom parameters constrained |
S = 0.99 | w = 1/[σ2(Fo2) + (0.0758P)2 + 6.8758P] where P = (Fo2 + 2Fc2)/3 |
1461 reflections | (Δ/σ)max < 0.001 |
100 parameters | Δρmax = 0.24 e Å−3 |
0 restraints | Δρmin = −0.19 e Å−3 |
Crystal data top
C7H10N2O2 | V = 1670 (2) Å3 |
Mr = 154.17 | Z = 8 |
Monoclinic, C2/c | Mo Kα radiation |
a = 17.822 (12) Å | µ = 0.09 mm−1 |
b = 4.850 (3) Å | T = 293 K |
c = 19.783 (14) Å | 0.20 × 0.09 × 0.06 mm |
β = 102.370 (9)° | |
Data collection top
APEX II diffractometer | 1461 independent reflections |
Absorption correction: empirical (using intensity measurements) software bruker | 871 reflections with I > 2σ(I) |
Tmin = 0.552, Tmax = 0.746 | Rint = 0.075 |
8010 measured reflections | |
Refinement top
R[F2 > 2σ(F2)] = 0.074 | 0 restraints |
wR(F2) = 0.228 | H-atom parameters constrained |
S = 0.99 | Δρmax = 0.24 e Å−3 |
1461 reflections | Δρmin = −0.19 e Å−3 |
100 parameters | |
Special details top
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 R- factors based on ALL data will be
even larger. |
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2) top | x | y | z | Uiso*/Ueq | |
C1 | 0.1212 (3) | 0.3506 (9) | −0.0069 (2) | 0.0514 (11) | |
C2 | 0.1700 (2) | 0.1805 (8) | 0.1933 (2) | 0.0475 (11) | |
C3 | 0.2245 (3) | 0.2668 (10) | 0.0929 (2) | 0.0546 (12) | |
H3A | 0.2521 | 0.4174 | 0.0770 | 0.066* | |
H3B | 0.2606 | 0.1171 | 0.1069 | 0.066* | |
C4 | 0.0588 (3) | 0.2240 (10) | −0.0579 (2) | 0.0621 (13) | |
H4 | 0.0581 | 0.0330 | −0.0621 | 0.075* | |
C5 | 0.0052 (3) | 0.3612 (12) | −0.0967 (3) | 0.0781 (16) | |
H5A | 0.0044 | 0.5525 | −0.0936 | 0.094* | |
H5B | −0.0330 | 0.2699 | −0.1281 | 0.094* | |
C6 | 0.1402 (3) | 0.3040 (10) | 0.2498 (2) | 0.0596 (13) | |
H6 | 0.1441 | 0.4941 | 0.2558 | 0.071* | |
C7 | 0.1092 (4) | 0.1646 (12) | 0.2913 (3) | 0.101 (2) | |
H7A | 0.1045 | −0.0258 | 0.2864 | 0.121* | |
H7B | 0.0911 | 0.2533 | 0.3263 | 0.121* | |
N1 | 0.1650 (2) | 0.1751 (7) | 0.03660 (17) | 0.0550 (10) | |
H1 | 0.1572 | 0.0010 | 0.0306 | 0.066* | |
N2 | 0.1961 (2) | 0.3576 (7) | 0.15207 (17) | 0.0505 (10) | |
H2 | 0.1960 | 0.5310 | 0.1611 | 0.061* | |
O1 | 0.1329 (2) | 0.6015 (6) | −0.00422 (18) | 0.0701 (11) | |
O2 | 0.17040 (19) | −0.0707 (6) | 0.18383 (17) | 0.0639 (10) | |
Atomic displacement parameters (Å2) top | U11 | U22 | U33 | U12 | U13 | U23 |
C1 | 0.068 (3) | 0.040 (2) | 0.049 (2) | 0.006 (2) | 0.017 (2) | −0.001 (2) |
C2 | 0.055 (3) | 0.037 (2) | 0.047 (2) | 0.0042 (19) | 0.003 (2) | 0.0022 (19) |
C3 | 0.066 (3) | 0.048 (3) | 0.050 (3) | 0.004 (2) | 0.013 (2) | 0.003 (2) |
C4 | 0.091 (4) | 0.045 (3) | 0.048 (3) | 0.002 (3) | 0.011 (3) | −0.008 (2) |
C5 | 0.082 (4) | 0.067 (3) | 0.080 (4) | −0.007 (3) | 0.006 (3) | −0.002 (3) |
C6 | 0.081 (3) | 0.046 (3) | 0.055 (3) | 0.006 (2) | 0.022 (3) | −0.001 (2) |
C7 | 0.145 (6) | 0.067 (4) | 0.117 (5) | 0.016 (4) | 0.085 (5) | 0.013 (4) |
N1 | 0.083 (3) | 0.039 (2) | 0.042 (2) | −0.0007 (19) | 0.0122 (19) | −0.0014 (16) |
N2 | 0.071 (3) | 0.0359 (19) | 0.044 (2) | −0.0018 (17) | 0.0110 (18) | −0.0036 (16) |
O1 | 0.090 (3) | 0.0323 (17) | 0.083 (2) | −0.0001 (16) | 0.0084 (19) | 0.0018 (16) |
O2 | 0.091 (3) | 0.0319 (17) | 0.073 (2) | 0.0025 (15) | 0.0249 (19) | −0.0025 (15) |
Geometric parameters (Å, º) top
C1—O1 | 1.234 (5) | C4—C5 | 1.277 (7) |
C1—N1 | 1.336 (5) | C4—H4 | 0.9300 |
C1—C4 | 1.467 (7) | C5—H5A | 0.9300 |
C2—O2 | 1.233 (5) | C5—H5B | 0.9300 |
C2—N2 | 1.334 (5) | C6—C7 | 1.277 (7) |
C2—C6 | 1.466 (6) | C6—H6 | 0.9300 |
C3—N1 | 1.435 (6) | C7—H7A | 0.9300 |
C3—N2 | 1.439 (5) | C7—H7B | 0.9300 |
C3—H3A | 0.9700 | N1—H1 | 0.8600 |
C3—H3B | 0.9700 | N2—H2 | 0.8600 |
| | | |
O1—C1—N1 | 122.0 (4) | C4—C5—H5A | 120.0 |
O1—C1—C4 | 122.6 (4) | C4—C5—H5B | 120.0 |
N1—C1—C4 | 115.4 (4) | H5A—C5—H5B | 120.0 |
O2—C2—N2 | 122.0 (4) | C7—C6—C2 | 123.5 (5) |
O2—C2—C6 | 122.3 (4) | C7—C6—H6 | 118.3 |
N2—C2—C6 | 115.7 (4) | C2—C6—H6 | 118.3 |
N1—C3—N2 | 113.3 (4) | C6—C7—H7A | 120.0 |
N1—C3—H3A | 108.9 | C6—C7—H7B | 120.0 |
N2—C3—H3A | 108.9 | H7A—C7—H7B | 120.0 |
N1—C3—H3B | 108.9 | C1—N1—C3 | 122.4 (4) |
N2—C3—H3B | 108.9 | C1—N1—H1 | 118.8 |
H3A—C3—H3B | 107.7 | C3—N1—H1 | 118.8 |
C5—C4—C1 | 123.7 (5) | C2—N2—C3 | 121.9 (4) |
C5—C4—H4 | 118.1 | C2—N2—H2 | 119.0 |
C1—C4—H4 | 118.1 | C3—N2—H2 | 119.0 |
Experimental details
Crystal data |
Chemical formula | C7H10N2O2 |
Mr | 154.17 |
Crystal system, space group | Monoclinic, C2/c |
Temperature (K) | 293 |
a, b, c (Å) | 17.822 (12), 4.850 (3), 19.783 (14) |
β (°) | 102.370 (9) |
V (Å3) | 1670 (2) |
Z | 8 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.20 × 0.09 × 0.06 |
|
Data collection |
Diffractometer | APEX II diffractometer |
Absorption correction | Empirical (using intensity measurements) software bruker |
Tmin, Tmax | 0.552, 0.746 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 8010, 1461, 871 |
Rint | 0.075 |
(sin θ/λ)max (Å−1) | 0.595 |
|
Refinement |
R[F2 > 2σ(F2)], wR(F2), S | 0.074, 0.228, 0.99 |
No. of reflections | 1461 |
No. of parameters | 100 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.24, −0.19 |
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