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2-Acetyl-1,1,3,3-tetra­methyl­guanidine

aFakultät Chemie/Organische Chemie, Hochschule Aalen, Beethovenstrasse 1, D-73430 Aalen, Germany
*Correspondence e-mail: Ioannis.Tiritiris@htw-aalen.de

(Received 17 September 2012; accepted 18 September 2012; online 26 September 2012)

In the mol­ecule of the title compound, C7H15N3O, the central C atom is surrounded in a nearly ideal trigonal–planar geometry by three N atoms. The C—N bond lengths in the CN3 unit are 1.3353 (13), 1.3463 (12) and 1.3541 (13) Å, indicating an inter­mediate character between a single and a double bond for each C—N bond. The bonds between the N atoms and the terminal C-methyl groups all have values close to that of a typical single bond [1.4526 (13)–1.4614 (14) Å]. In the crystal, the guanidine mol­ecules are connected by weak C—H⋯O and C—H⋯N hydrogen bonds, generating layers parallel to the ab plane.

Related literature

For the preparation of N-acetyl-N′,N′,N′′,N′′-tetra­methyl­guanidine, see: Kessler & Leibfritz (1970[Kessler, H. & Leibfritz, D. (1970). Tetrahedron, 26, 1805-1820.]). For the preparation and properties of acyl­guanidines, see: Matsumoto & Rapoport (1968[Matsumoto, K. & Rapoport, H. (1968). J. Org. Chem. 33, 552-558.]).

[Scheme 1]

Experimental

Crystal data
  • C7H15N3O

  • Mr = 157.22

  • Monoclinic, P 21 /n

  • a = 6.7625 (3) Å

  • b = 17.8610 (8) Å

  • c = 7.6687 (4) Å

  • β = 103.107 (2)°

  • V = 902.13 (7) Å3

  • Z = 4

  • Mo Kα radiation

  • μ = 0.08 mm−1

  • T = 100 K

  • 0.22 × 0.18 × 0.16 mm

Data collection
  • Bruker Kappa APEXII Duo diffractometer

  • 17552 measured reflections

  • 2758 independent reflections

  • 2396 reflections with I > 2σ(I)

  • Rint = 0.031

Refinement
  • R[F2 > 2σ(F2)] = 0.046

  • wR(F2) = 0.117

  • S = 1.10

  • 2758 reflections

  • 105 parameters

  • H-atom parameters constrained

  • Δρmax = 0.29 e Å−3

  • Δρmin = −0.22 e Å−3

Table 1
Hydrogen-bond geometry (Å, °)

D—H⋯A D—H H⋯A DA D—H⋯A
C3—H3B⋯O1i 0.98 2.60 3.4807 (10) 150
C5—H5A⋯N3ii 0.98 2.61 3.5456 (15) 160
Symmetry codes: (i) x+1, y, z; (ii) -x+1, -y, -z+1.

Data collection: APEX2 (Bruker, 2008[Bruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); cell refinement: SAINT (Bruker, 2008[Bruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.]); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008[Sheldrick, G. M. (2008). Acta Cryst. A64, 112-122.]); molecular graphics: DIAMOND (Brandenburg & Putz, 2005[Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.]); software used to prepare material for publication: SHELXL97.

Supporting information


Comment top

The preparation and properties of various acylguanidines have been described in the literature several years ago (Matsumoto & Rapoport, 1968). While in acylguanidines it can be distinguished between the acylamino and and acylimino form, the increase in pKa going from acylimino- to acylaminoguanidines was explained by conjugation of the guanidine part with the acetyl group. The here presented acylimino type title compound was described in the literature as a colorless liquid (Kessler & Leibfritz, 1970), but quite recently it was possible to obtain single crystals and to elucidate its hitherto unknown crystal structure. According to the structure analysis, the C—N bond lengths of the CN3 unit are: C1—N3 = 1.3353 (13) Å, C1—N2 = 1.3463 (12) Å and C1—N1 = 1.3541 (13) Å. They appear intermediate between those expected for single and double C—N bonds (1.46 and 1.28 Å, respectively). The N—C1—N angles are: 117.99 (9)° (N1—C1—N2), 118.62 (9)° (N2—C1—N3) and 123.11 (9)° (N1—C1—N3), which indicates only a slight deviation from an ideal trigonal–planar surrounding of the carbon centre by the N atoms. The bonds between the N atoms and the terminal C-methyl groups all have values close to a typical single bond (1.4526 (13)–1.4614 (14) Å). The bond lengths in the acetyl group are: C6—O1 = 1.2325 (13) Å, C6—C7 = 1.5109 (15) Å and N3—C6 = 1.3554 (13) Å. The C—O bond shows the expected double-bond character while the C—C bond is typical for a single bond. The dihedral angle C1—N3—C6—C7 is -166.23 (10)° and the angle between the planes N1/C1/N2 and C7/C6/O1 is 58.49 (10)°, which shows a significant twisting of the acetyl group relative to the CN3 plane (Fig. 1). Only weak C—H···O and C—H···N hydrogen bonds between methyl H atoms and carbonyl O atoms or N atoms of neighboring acetylguanidine molecules have been determined [d(H···O) = 2.60 Å and d(H···N) = 2.61 Å] (Table 1), generating chains along (100) (Fig. 2).

Related literature top

For the preparation of N-acetyl-N',N',N'',N''-tetramethylguanidine, see: Kessler & Leibfritz (1970). For the preparation and properties of acylguanidines, see: Matsumoto & Rapoport (1968).

Experimental top

The title compound was obtained by heating two equivalents of N',N',N'',N''-tetramethylguanidine with one equivalent acetyl chloride in acetonitrile for 2 h under reflux (Kessler & Leibfritz, 1970). After cooling at room temperature the precipitated N',N',N'',N''-tetramethylguanidinium chloride was filtered off and the solvent was removed. The residue was redissolved in diethylether and the insoluble part was filtered off. After evaporation of the solvent a colorless liquid has been obtained. The title compound crystallized spontaneously after several days during standing at room temperature, giving colorless single crystals suitable for X-ray analysis. 1H NMR (500 MHz, CDCl3/TMS): δ = 2.10 (s, 3 H, CH3), 2.90 [s, 12 H, N(CH3)2]. 13C NMR (125 MHz, CDCl3/TMS): δ = 26.3 (CH3), 40.0 [N(CH3)2], 166.7 (CN), 178.8 (CO).

Refinement top

The H atoms of the methyl groups were allowed to rotate with a fixed angle around the C—N or C—C bond to best fit the experimental electron density, with U(H) set to 1.5 Ueq(C) and d(C—H) = 0.98 Å.

Structure description top

The preparation and properties of various acylguanidines have been described in the literature several years ago (Matsumoto & Rapoport, 1968). While in acylguanidines it can be distinguished between the acylamino and and acylimino form, the increase in pKa going from acylimino- to acylaminoguanidines was explained by conjugation of the guanidine part with the acetyl group. The here presented acylimino type title compound was described in the literature as a colorless liquid (Kessler & Leibfritz, 1970), but quite recently it was possible to obtain single crystals and to elucidate its hitherto unknown crystal structure. According to the structure analysis, the C—N bond lengths of the CN3 unit are: C1—N3 = 1.3353 (13) Å, C1—N2 = 1.3463 (12) Å and C1—N1 = 1.3541 (13) Å. They appear intermediate between those expected for single and double C—N bonds (1.46 and 1.28 Å, respectively). The N—C1—N angles are: 117.99 (9)° (N1—C1—N2), 118.62 (9)° (N2—C1—N3) and 123.11 (9)° (N1—C1—N3), which indicates only a slight deviation from an ideal trigonal–planar surrounding of the carbon centre by the N atoms. The bonds between the N atoms and the terminal C-methyl groups all have values close to a typical single bond (1.4526 (13)–1.4614 (14) Å). The bond lengths in the acetyl group are: C6—O1 = 1.2325 (13) Å, C6—C7 = 1.5109 (15) Å and N3—C6 = 1.3554 (13) Å. The C—O bond shows the expected double-bond character while the C—C bond is typical for a single bond. The dihedral angle C1—N3—C6—C7 is -166.23 (10)° and the angle between the planes N1/C1/N2 and C7/C6/O1 is 58.49 (10)°, which shows a significant twisting of the acetyl group relative to the CN3 plane (Fig. 1). Only weak C—H···O and C—H···N hydrogen bonds between methyl H atoms and carbonyl O atoms or N atoms of neighboring acetylguanidine molecules have been determined [d(H···O) = 2.60 Å and d(H···N) = 2.61 Å] (Table 1), generating chains along (100) (Fig. 2).

For the preparation of N-acetyl-N',N',N'',N''-tetramethylguanidine, see: Kessler & Leibfritz (1970). For the preparation and properties of acylguanidines, see: Matsumoto & Rapoport (1968).

Computing details top

Data collection: APEX2 (Bruker, 2008); cell refinement: SAINT (Bruker, 2008); data reduction: SAINT (Bruker, 2008); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: DIAMOND (Brandenburg & Putz, 2005); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008).

Figures top
[Figure 1] Fig. 1. The structure of the title compound with atom labels and 50% probability displacement ellipsoids.
[Figure 2] Fig. 2. C—H···O and C—H···N hydrogen bonds between the guanidine molecules, ab view. The hydrogen bonds are indicated by dashed lines.
2-Acetyl-1,1,3,3-tetramethylguanidine top
Crystal data top
C7H15N3OF(000) = 344
Mr = 157.22Dx = 1.158 Mg m3
Monoclinic, P21/nMo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ynCell parameters from 17552 reflections
a = 6.7625 (3) Åθ = 2.3–30.6°
b = 17.8610 (8) ŵ = 0.08 mm1
c = 7.6687 (4) ÅT = 100 K
β = 103.107 (2)°Block, colourless
V = 902.13 (7) Å30.22 × 0.18 × 0.16 mm
Z = 4
Data collection top
Bruker Kappa APEXII Duo
diffractometer
2396 reflections with I > 2σ(I)
Radiation source: sealed tubeRint = 0.031
Graphite monochromatorθmax = 30.6°, θmin = 2.3°
φ scans, and ω scansh = 99
17552 measured reflectionsk = 2525
2758 independent reflectionsl = 1010
Refinement top
Refinement on F2Primary atom site location: structure-invariant direct methods
Least-squares matrix: fullSecondary atom site location: difference Fourier map
R[F2 > 2σ(F2)] = 0.046Hydrogen site location: difference Fourier map
wR(F2) = 0.117H-atom parameters constrained
S = 1.10 w = 1/[σ2(Fo2) + (0.0482P)2 + 0.2933P]
where P = (Fo2 + 2Fc2)/3
2758 reflections(Δ/σ)max < 0.001
105 parametersΔρmax = 0.29 e Å3
0 restraintsΔρmin = 0.22 e Å3
Crystal data top
C7H15N3OV = 902.13 (7) Å3
Mr = 157.22Z = 4
Monoclinic, P21/nMo Kα radiation
a = 6.7625 (3) ŵ = 0.08 mm1
b = 17.8610 (8) ÅT = 100 K
c = 7.6687 (4) Å0.22 × 0.18 × 0.16 mm
β = 103.107 (2)°
Data collection top
Bruker Kappa APEXII Duo
diffractometer
2396 reflections with I > 2σ(I)
17552 measured reflectionsRint = 0.031
2758 independent reflections
Refinement top
R[F2 > 2σ(F2)] = 0.0460 restraints
wR(F2) = 0.117H-atom parameters constrained
S = 1.10Δρmax = 0.29 e Å3
2758 reflectionsΔρmin = 0.22 e Å3
105 parameters
Special details top

Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'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 > σ(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
xyzUiso*/Ueq
C10.47479 (14)0.12793 (5)0.62624 (13)0.01806 (19)
N10.59364 (13)0.17507 (5)0.74330 (11)0.02142 (19)
N20.51335 (13)0.12040 (5)0.46244 (11)0.02139 (19)
N30.33436 (14)0.08392 (5)0.67072 (13)0.02306 (19)
C20.60794 (18)0.16825 (8)0.93451 (14)0.0306 (3)
H2A0.50620.20060.96910.046*
H2B0.74390.18340.99990.046*
H2C0.58340.11610.96360.046*
C30.66323 (17)0.24704 (6)0.69034 (16)0.0266 (2)
H3A0.61700.25320.56050.040*
H3B0.81190.24880.72360.040*
H3C0.60760.28740.75130.040*
C40.71272 (17)0.13280 (7)0.42383 (15)0.0281 (2)
H4A0.81190.14370.53550.042*
H4B0.70540.17520.34150.042*
H4C0.75460.08780.36860.042*
C50.37019 (18)0.08048 (6)0.32279 (15)0.0284 (2)
H5A0.41770.02900.31450.043*
H5B0.36010.10590.20790.043*
H5C0.23640.07960.35200.043*
C60.19940 (15)0.11382 (6)0.75754 (14)0.0223 (2)
O10.15957 (12)0.18080 (5)0.76760 (12)0.0296 (2)
C70.08363 (19)0.05584 (8)0.83782 (18)0.0348 (3)
H7A0.00300.08080.91200.052*
H7B0.17960.02110.91190.052*
H7C0.00670.02800.74160.052*
Atomic displacement parameters (Å2) top
U11U22U33U12U13U23
C10.0184 (4)0.0164 (4)0.0188 (4)0.0027 (3)0.0031 (3)0.0017 (3)
N10.0197 (4)0.0264 (4)0.0180 (4)0.0044 (3)0.0039 (3)0.0012 (3)
N20.0224 (4)0.0225 (4)0.0187 (4)0.0006 (3)0.0036 (3)0.0016 (3)
N30.0244 (4)0.0172 (4)0.0293 (4)0.0019 (3)0.0096 (3)0.0001 (3)
C20.0254 (5)0.0473 (7)0.0180 (5)0.0033 (5)0.0027 (4)0.0017 (4)
C30.0230 (5)0.0250 (5)0.0313 (5)0.0066 (4)0.0053 (4)0.0039 (4)
C40.0263 (5)0.0373 (6)0.0229 (5)0.0019 (4)0.0102 (4)0.0010 (4)
C50.0340 (6)0.0226 (5)0.0245 (5)0.0009 (4)0.0016 (4)0.0064 (4)
C60.0183 (4)0.0243 (5)0.0240 (5)0.0032 (3)0.0043 (4)0.0002 (4)
O10.0233 (4)0.0252 (4)0.0408 (5)0.0008 (3)0.0086 (3)0.0054 (3)
C70.0309 (6)0.0358 (6)0.0410 (6)0.0085 (5)0.0151 (5)0.0053 (5)
Geometric parameters (Å, º) top
C1—N31.3353 (13)C3—H3C0.9800
C1—N21.3463 (12)C4—H4A0.9800
C1—N11.3541 (13)C4—H4B0.9800
N1—C21.4526 (13)C4—H4C0.9800
N1—C31.4579 (14)C5—H5A0.9800
N2—C51.4568 (13)C5—H5B0.9800
N2—C41.4614 (14)C5—H5C0.9800
N3—C61.3554 (13)C6—O11.2325 (13)
C2—H2A0.9800C6—C71.5109 (15)
C2—H2B0.9800C7—H7A0.9800
C2—H2C0.9800C7—H7B0.9800
C3—H3A0.9800C7—H7C0.9800
C3—H3B0.9800
N3—C1—N2118.62 (9)N2—C4—H4A109.5
N3—C1—N1123.11 (9)N2—C4—H4B109.5
N2—C1—N1117.99 (9)H4A—C4—H4B109.5
C1—N1—C2120.71 (9)N2—C4—H4C109.5
C1—N1—C3122.97 (8)H4A—C4—H4C109.5
C2—N1—C3113.79 (9)H4B—C4—H4C109.5
C1—N2—C5119.86 (9)N2—C5—H5A109.5
C1—N2—C4123.83 (9)N2—C5—H5B109.5
C5—N2—C4114.53 (9)H5A—C5—H5B109.5
C1—N3—C6119.38 (9)N2—C5—H5C109.5
N1—C2—H2A109.5H5A—C5—H5C109.5
N1—C2—H2B109.5H5B—C5—H5C109.5
H2A—C2—H2B109.5O1—C6—N3126.46 (10)
N1—C2—H2C109.5O1—C6—C7119.93 (10)
H2A—C2—H2C109.5N3—C6—C7113.51 (10)
H2B—C2—H2C109.5C6—C7—H7A109.5
N1—C3—H3A109.5C6—C7—H7B109.5
N1—C3—H3B109.5H7A—C7—H7B109.5
H3A—C3—H3B109.5C6—C7—H7C109.5
N1—C3—H3C109.5H7A—C7—H7C109.5
H3A—C3—H3C109.5H7B—C7—H7C109.5
H3B—C3—H3C109.5
N3—C1—N1—C214.29 (15)N3—C1—N2—C4147.74 (10)
N2—C1—N1—C2159.51 (10)N1—C1—N2—C426.35 (15)
N3—C1—N1—C3146.52 (10)N2—C1—N3—C6136.75 (10)
N2—C1—N1—C339.68 (14)N1—C1—N3—C649.48 (14)
N3—C1—N2—C516.15 (14)C1—N3—C6—O117.39 (17)
N1—C1—N2—C5169.76 (9)C1—N3—C6—C7166.23 (10)
Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3B···O1i0.982.603.4807 (10)150
C5—H5A···N3ii0.982.613.5456 (15)160
Symmetry codes: (i) x+1, y, z; (ii) x+1, y, z+1.

Experimental details

Crystal data
Chemical formulaC7H15N3O
Mr157.22
Crystal system, space groupMonoclinic, P21/n
Temperature (K)100
a, b, c (Å)6.7625 (3), 17.8610 (8), 7.6687 (4)
β (°) 103.107 (2)
V3)902.13 (7)
Z4
Radiation typeMo Kα
µ (mm1)0.08
Crystal size (mm)0.22 × 0.18 × 0.16
Data collection
DiffractometerBruker Kappa APEXII Duo
Absorption correction
No. of measured, independent and
observed [I > 2σ(I)] reflections
17552, 2758, 2396
Rint0.031
(sin θ/λ)max1)0.716
Refinement
R[F2 > 2σ(F2)], wR(F2), S 0.046, 0.117, 1.10
No. of reflections2758
No. of parameters105
H-atom treatmentH-atom parameters constrained
Δρmax, Δρmin (e Å3)0.29, 0.22

Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005).

Hydrogen-bond geometry (Å, º) top
D—H···AD—HH···AD···AD—H···A
C3—H3B···O1i0.982.603.4807 (10)149.6
C5—H5A···N3ii0.982.613.5456 (15)159.9
Symmetry codes: (i) x+1, y, z; (ii) x+1, y, z+1.
 

Acknowledgements

The author thanks Dr W. Frey (Institut für Organische Chemie, Universität Stuttgart) for measuring the X-ray data.

References

First citationBrandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany.  Google Scholar
First citationBruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA.  Google Scholar
First citationKessler, H. & Leibfritz, D. (1970). Tetrahedron, 26, 1805–1820.  CrossRef Web of Science Google Scholar
First citationMatsumoto, K. & Rapoport, H. (1968). J. Org. Chem. 33, 552–558.  CrossRef CAS Web of Science Google Scholar
First citationSheldrick, G. M. (2008). Acta Cryst. A64, 112–122.  Web of Science CrossRef CAS IUCr Journals Google Scholar

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ISSN: 2056-9890
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