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Acta Crystallogr Sect E Struct Rep Online. 2008 February 1; 64(Pt 2): o355.
Published online 2008 January 4. doi:  10.1107/S1600536807067232
PMCID: PMC2960435

Urea–N,N-dimethyl­acetamide (1/1)

Abstract

Urea forms a 1:1 solvate with N,N-dimethyl­acetamide (DMA) [systematic name: diamino­methanal–N,N-dimethyl­acetamide (1/1), C4H9NO·CH4N2O] with both mol­ecules positioned on a twofold axis, giving rise to rotational disorder of the DMA mol­ecule. The mol­ecules display a layered structure in which urea mol­ecules form hydrogen-bonded ribbons bounded by mol­ecules of solvent.

Related literature

For details on experimental methods used to obtain this crystalline compound, see: Florence et al. (2003 [triangle]). For crystal structures of urea, see: Fernandes et al. (2007 [triangle]); Vaughan & Donohue (1952 [triangle]), and references therein; Swaminathan et al. (1984 [triangle]); Pryor & Sanger (1970 [triangle]); Guth et al. (1980 [triangle]); Weber et al. (2002 [triangle]). For related literature, see: Etter (1990 [triangle]).

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Object name is e-64-0o355-scheme1.jpg

Experimental

Crystal data

  • C4H9NO·CH4N2O
  • M r = 147.18
  • Monoclinic, An external file that holds a picture, illustration, etc.
Object name is e-64-0o355-efi4.jpg
  • a = 7.2770 (3) Å
  • b = 17.5394 (9) Å
  • c = 7.3789 (4) Å
  • β = 119.450 (3)°
  • V = 820.11 (7) Å3
  • Z = 4
  • Mo Kα radiation
  • μ = 0.09 mm−1
  • T = 120 K
  • 0.40 × 0.12 × 0.04 mm

Data collection

  • Bruker–Nonius KappaCCD diffractometer
  • Absorption correction: multi-scan (SADABS; Bruker, 2007 [triangle]) T min = 0.867, T max = 1 (expected range = 0.864–0.996)
  • 5338 measured reflections
  • 941 independent reflections
  • 552 reflections with I > 2.0σ(I)
  • R int = 0.048

Refinement

  • R[F 2 > 2σ(F 2)] = 0.050
  • wR(F 2) = 0.150
  • S = 0.89
  • 939 reflections
  • 63 parameters
  • H atoms treated by a mixture of independent and constrained refinement
  • Δρmax = 0.31 e Å−3
  • Δρmin = −0.39 e Å−3

Data collection: COLLECT (Hooft, 1998 [triangle]); cell refinement: DENZO (Otwinowski & Minor, 1997 [triangle]) and COLLECT; data reduction: DENZO and COLLECT; program(s) used to solve structure: SIR92 (Altomare et al., 1994 [triangle]); program(s) used to refine structure: CRYSTALS (Betteridge et al., 2003 [triangle]); molecular graphics: ORTEP-3 (Farrugia, 1997 [triangle]) and Mercury (Macrae et al., 2006 [triangle]); software used to prepare material for publication: enCIFer (Allen et al., 2004 [triangle]) and publCIF (Westrip, 2008 [triangle]).

Table 1
Hydrogen-bond geometry (Å, °)

Supplementary Material

Crystal structure: contains datablocks global, I. DOI: 10.1107/S1600536807067232/ga2020sup1.cif

Structure factors: contains datablocks I. DOI: 10.1107/S1600536807067232/ga2020Isup2.hkl

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Acknowledgments

The authors thank the Basic Technology programme of the UK Research Councils for funding this work under the project Control and Prediction of the Organic Solid State (http://www.cposs.org.uk). We also thank the EPSRC National X-ray Crystallography Service at the University of Southampton for the data collection.

supplementary crystallographic information

Comment

The crystal structure of urea has been widely studied (see for example, Vaughan and Donohue (1952) and references therein; Swaminathan et al. (1984), Pryor and Sanger (1970), Guth et al. (1980) and Weber et al. (2002)). This previously unreported crystalline solvate of urea was discovered during an investigation into the influence of different crystallization solvents on urea crystal morphology (see also Fernandes et al., 2007). The sample was obtained by slow evaporation from a saturated N,N-dimethylacetamide (DMA) solution at 298 K and identified by using multi-sample foil transmission X-ray powder diffraction analysis (Florence et al., 2003). Subsequent recrystallization produced a single-crystal suitable for X-ray diffraction at 120 K (Fig. 1).

Both molecules lie over a two fold rotation axis resulting in the DMA being disordered (see refinement section for details). Each urea molecule interacts with adjacent urea molecules via contact 1 (Fig. 2, entry 1, Table 1), forming a hydrogen bonded ribbon that runs in the direction [-1 0 1]. Molecules of DMA lie on the edge of the ribbons, connected through a second hydrogen bond (contact 2), (entry 2, Table 1).The DMA-bordered ribbons of urea pack side-by-side to form a two-dimensional sheet.

Experimental

The compound was sourced from Sigma-Aldrich and used as supplied. A single-crystal sample of the 1/1 solvate was recrystallized from a saturated N,N-dimethylacetamide solution by isothermal solvent evaporation at room temperature (298 K).

Refinement

The DMA moiety was found to be disordered over a 2-fold rotation axis, with atoms C7 and O9 sitting on this axis. The site occupancies of N4 and C8 were consequently fixed to 1/2, whilst that of C6 was fixed to 1.0 as this atom acts as a methyl carbon both attached to N4 and to C8 in the disordered model. All non-H-atoms were modelled with anisotropic displacement parameters. H-atoms attached to N3 were located in a difference Fourier map and their positions were freely refined. H-atoms attached to C6 and C7 were positioned geometrically, taking into account disorder and occupancy of the parents atoms, and their positions were fixed during refinement. Uiso(H) were assigned in the range 1.2–1.5 times Ueq of the parent atom.

Note that both the (1 1 0) and the (-2 0 2) reflections were excluded from the final refinement as they were significant outliers on the Fo versus Fc plot.

Figures

Fig. 1.
The molecular structure of the title compound showing 50% probablility displacement ellipsoids. Hydrogen atoms have been omitted for clarity. A twofold axis runs through C1, O2 of urea and O9, C7 of DMA, giving rise to the rotational disorder of the DMA ...
Fig. 2.
Selected molecular packing, viewed down the a axis, of the title compound illustrating the hydrogen bonded network. Urea molecules (green) form an R22(8) motif (Etter, 1990) involving contact 1 (entry 1, Table 1) that propagates to form an infinite ribbon. ...

Crystal data

C4H9NO·CH4N2OF000 = 320
Mr = 147.18Dx = 1.192 Mg m3
Monoclinic, C2/cMelting point: 406 K
Hall symbol: -C 2ycMo Kα radiation λ = 0.71073 Å
a = 7.2770 (3) ÅCell parameters from 2218 reflections
b = 17.5394 (9) Åθ = 3–27º
c = 7.3789 (4) ŵ = 0.09 mm1
β = 119.450 (3)ºT = 120 K
V = 820.11 (7) Å3Lath, colourless
Z = 40.40 × 0.12 × 0.04 mm

Data collection

Bruker–Nonius KappaCCD diffractometer941 independent reflections
Radiation source: Bruker-Nonius FR591 rotating anode552 reflections with I > 2.0σ(I)
Monochromator: graphiteRint = 0.048
Detector resolution: 9.091 pixels mm-1θmax = 27.6º
T = 120(2) Kθmin = 3.4º
[var phi] & ω scansh = −9→9
Absorption correction: multi-scan(SADABS; Bruker, 2007)k = −22→22
Tmin = 0.867, Tmax = 1l = −9→9
5338 measured reflections

Refinement

Refinement on F2Hydrogen site location: geom + difmap
Least-squares matrix: fullH atoms treated by a mixture of independent and constrained refinement
R[F2 > 2σ(F2)] = 0.050  Method = Modified Sheldrick w = 1/[σ2(F2) + ( 0.07P)2] ,where P = (max(Fo2,0) + 2Fc2)/3
wR(F2) = 0.150(Δ/σ)max = 0.0001
S = 0.89Δρmax = 0.31 e Å3
939 reflectionsΔρmin = −0.39 e Å3
63 parametersExtinction correction: none
Primary atom site location: structure-invariant direct methods

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å2)

xyzUiso*/UeqOcc. (<1)
C10.00000.30587 (14)0.25000.0293
O20.00000.23473 (9)0.25000.0380
N30.1649 (2)0.34642 (10)0.3935 (3)0.0360
N40.0668 (4)0.37977 (18)0.7962 (5)0.03470.5000
C60.2835 (3)0.40670 (13)0.9670 (4)0.0525
C70.00000.29897 (16)0.75000.0508
C8−0.0735 (5)0.4351 (2)0.6946 (6)0.03470.5000
O90.00000.50307 (11)0.75000.0628
H310.264 (3)0.3224 (11)0.499 (4)0.0365*
H320.158 (3)0.3959 (13)0.393 (3)0.0360*
H71−0.14090.29690.63800.0608*0.5000
H720.00740.27600.86960.0608*0.5000
H730.09080.27320.71240.0608*0.5000
H610.28800.46080.96650.0542*0.5000
H620.30560.38941.09800.0542*0.5000
H630.38890.38660.94090.0542*0.5000
H640.28270.35260.96570.0542*0.5000
H650.31080.42441.09940.0542*0.5000
H660.38850.42500.93770.0542*0.5000

Atomic displacement parameters (Å2)

U11U22U33U12U13U23
C10.0239 (11)0.0284 (14)0.0251 (13)0.00000.0038 (10)0.0000
O20.0315 (9)0.0245 (10)0.0342 (11)0.0000−0.0022 (8)0.0000
N30.0289 (8)0.0261 (9)0.0325 (10)−0.0009 (6)−0.0006 (7)0.0011 (7)
N40.0290 (18)0.0271 (17)0.038 (2)0.0003 (11)0.0085 (16)−0.0020 (14)
C60.0327 (10)0.0554 (14)0.0474 (14)−0.0003 (9)0.0026 (10)0.0046 (11)
C70.0663 (19)0.0236 (14)0.059 (2)0.00000.0286 (17)0.0000
C80.0332 (19)0.030 (2)0.031 (2)−0.0004 (14)0.0084 (16)0.0008 (16)
O90.0855 (16)0.0210 (11)0.0587 (16)0.00000.0176 (13)0.0000

Geometric parameters (Å, °)

O9—C81.288 (4)C6—H630.9500
O9—C8i1.288 (4)C6—H640.9500
O2—C11.248 (3)C6—H650.9500
N4—C61.531 (4)C6—H610.9500
N4—C81.339 (5)C6—H660.9500
N4—C71.483 (4)C7—H72i0.9500
N3—C11.348 (2)C7—H73i0.9500
N3—H320.87 (2)C7—H71i0.9500
N3—H310.87 (2)C7—H710.9500
C6—C8i1.488 (5)C7—H720.9500
C6—H620.9500C7—H730.9500
C6—N4—C7124.9 (2)C8i—C6—H6172.00
C6—N4—C8115.5 (3)H62—C6—H63110.00
C7—N4—C8119.4 (3)H62—C6—H6472.00
C1—N3—H32119.8 (14)C8i—C6—H66109.00
H31—N3—H32120.7 (19)N4—C7—H71i75.00
C1—N3—H31118.4 (14)N4—C7—H72i119.00
N4—C8—C6i114.0 (3)N4—C7—H73109.00
O9—C8—N4114.2 (3)H71—C7—H72110.00
O9—C8—C6i131.8 (3)H71—C7—H73110.00
N4—C6—H61109.00N4—C7—H73i126.00
N4—C6—H62109.00H71—C7—H71i176.00
N4—C6—H63109.00H71—C7—H72i68.00
N4—C6—H6472.00H71—C7—H73i68.00
H61—C6—H63110.00H72—C7—H73110.00
H61—C6—H64178.00N4i—C7—H72119.00
H61—C6—H6572.00H71i—C7—H7268.00
H61—C6—H6668.00N4i—C7—H7175.00
N4—C6—H65124.00N4i—C7—H73126.00
N4—C6—H66122.00H71i—C7—H7368.00
H61—C6—H62110.00N4i—C7—H71i109.00
H62—C6—H66126.00N4i—C7—H72i109.00
C8i—C6—H62121.00N4i—C7—H73i109.00
H63—C6—H6468.00H71i—C7—H72i110.00
H63—C6—H65123.00H71i—C7—H73i110.00
C8i—C6—H63125.00N4—C7—H71109.00
H64—C6—H65110.00N4—C7—H72109.00
H64—C6—H66110.00O2—C1—N3121.84 (12)
C8i—C6—H64109.00O2—C1—N3ii121.84 (12)
H65—C6—H66110.00N3—C1—N3ii116.3 (2)
C8i—C6—H65109.00

Symmetry codes: (i) −x, y, −z+3/2; (ii) −x, y, −z+1/2.

Hydrogen-bond geometry (Å, °)

D—H···AD—HH···AD···AD—H···A
N3—H31···O2iii0.87 (2)2.06 (2)2.930 (2)180 (3)
N3—H32···O9iv0.87 (2)2.09 (2)2.878 (3)149.7 (19)

Symmetry codes: (iii) −x+1/2, −y+1/2, −z+1; (iv) −x, −y+1, −z+1.

Footnotes

Supplementary data and figures for this paper are available from the IUCr electronic archives (Reference: GA2020).

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