organic compounds
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
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). For the preparation and properties of acylguanidines, see: Matsumoto & Rapoport (1968).
Experimental
Crystal data
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Data collection
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Refinement
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Data collection: APEX2 (Bruker, 2008); cell SAINT (Bruker, 2008); data reduction: SAINT; 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.
Supporting information
https://doi.org/10.1107/S1600536812039724/zl2504sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536812039724/zl2504Isup2.hkl
Supporting information file. DOI: https://doi.org/10.1107/S1600536812039724/zl2504Isup3.cml
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 (C═N), 178.8 (C═O).
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.
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
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).
Data collection: APEX2 (Bruker, 2008); cell
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).C7H15N3O | F(000) = 344 |
Mr = 157.22 | Dx = 1.158 Mg m−3 |
Monoclinic, P21/n | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: -P 2yn | Cell parameters from 17552 reflections |
a = 6.7625 (3) Å | θ = 2.3–30.6° |
b = 17.8610 (8) Å | µ = 0.08 mm−1 |
c = 7.6687 (4) Å | T = 100 K |
β = 103.107 (2)° | Block, colourless |
V = 902.13 (7) Å3 | 0.22 × 0.18 × 0.16 mm |
Z = 4 |
Bruker Kappa APEXII Duo diffractometer | 2396 reflections with I > 2σ(I) |
Radiation source: sealed tube | Rint = 0.031 |
Graphite monochromator | θmax = 30.6°, θmin = 2.3° |
φ scans, and ω scans | h = −9→9 |
17552 measured reflections | k = −25→25 |
2758 independent reflections | l = −10→10 |
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)] = 0.046 | Hydrogen site location: difference Fourier map |
wR(F2) = 0.117 | H-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 parameters | Δρmax = 0.29 e Å−3 |
0 restraints | Δρmin = −0.22 e Å−3 |
C7H15N3O | V = 902.13 (7) Å3 |
Mr = 157.22 | Z = 4 |
Monoclinic, P21/n | Mo Kα radiation |
a = 6.7625 (3) Å | µ = 0.08 mm−1 |
b = 17.8610 (8) Å | T = 100 K |
c = 7.6687 (4) Å | 0.22 × 0.18 × 0.16 mm |
β = 103.107 (2)° |
Bruker Kappa APEXII Duo diffractometer | 2396 reflections with I > 2σ(I) |
17552 measured reflections | Rint = 0.031 |
2758 independent reflections |
R[F2 > 2σ(F2)] = 0.046 | 0 restraints |
wR(F2) = 0.117 | H-atom parameters constrained |
S = 1.10 | Δρmax = 0.29 e Å−3 |
2758 reflections | Δρmin = −0.22 e Å−3 |
105 parameters |
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. |
x | y | z | Uiso*/Ueq | ||
C1 | 0.47479 (14) | 0.12793 (5) | 0.62624 (13) | 0.01806 (19) | |
N1 | 0.59364 (13) | 0.17507 (5) | 0.74330 (11) | 0.02142 (19) | |
N2 | 0.51335 (13) | 0.12040 (5) | 0.46244 (11) | 0.02139 (19) | |
N3 | 0.33436 (14) | 0.08392 (5) | 0.67072 (13) | 0.02306 (19) | |
C2 | 0.60794 (18) | 0.16825 (8) | 0.93451 (14) | 0.0306 (3) | |
H2A | 0.5062 | 0.2006 | 0.9691 | 0.046* | |
H2B | 0.7439 | 0.1834 | 0.9999 | 0.046* | |
H2C | 0.5834 | 0.1161 | 0.9636 | 0.046* | |
C3 | 0.66323 (17) | 0.24704 (6) | 0.69034 (16) | 0.0266 (2) | |
H3A | 0.6170 | 0.2532 | 0.5605 | 0.040* | |
H3B | 0.8119 | 0.2488 | 0.7236 | 0.040* | |
H3C | 0.6076 | 0.2874 | 0.7513 | 0.040* | |
C4 | 0.71272 (17) | 0.13280 (7) | 0.42383 (15) | 0.0281 (2) | |
H4A | 0.8119 | 0.1437 | 0.5355 | 0.042* | |
H4B | 0.7054 | 0.1752 | 0.3415 | 0.042* | |
H4C | 0.7546 | 0.0878 | 0.3686 | 0.042* | |
C5 | 0.37019 (18) | 0.08048 (6) | 0.32279 (15) | 0.0284 (2) | |
H5A | 0.4177 | 0.0290 | 0.3145 | 0.043* | |
H5B | 0.3601 | 0.1059 | 0.2079 | 0.043* | |
H5C | 0.2364 | 0.0796 | 0.3520 | 0.043* | |
C6 | 0.19940 (15) | 0.11382 (6) | 0.75754 (14) | 0.0223 (2) | |
O1 | 0.15957 (12) | 0.18080 (5) | 0.76760 (12) | 0.0296 (2) | |
C7 | 0.08363 (19) | 0.05584 (8) | 0.83782 (18) | 0.0348 (3) | |
H7A | 0.0030 | 0.0808 | 0.9120 | 0.052* | |
H7B | 0.1796 | 0.0211 | 0.9119 | 0.052* | |
H7C | −0.0067 | 0.0280 | 0.7416 | 0.052* |
U11 | U22 | U33 | U12 | U13 | U23 | |
C1 | 0.0184 (4) | 0.0164 (4) | 0.0188 (4) | 0.0027 (3) | 0.0031 (3) | 0.0017 (3) |
N1 | 0.0197 (4) | 0.0264 (4) | 0.0180 (4) | −0.0044 (3) | 0.0039 (3) | −0.0012 (3) |
N2 | 0.0224 (4) | 0.0225 (4) | 0.0187 (4) | −0.0006 (3) | 0.0036 (3) | −0.0016 (3) |
N3 | 0.0244 (4) | 0.0172 (4) | 0.0293 (4) | −0.0019 (3) | 0.0096 (3) | 0.0001 (3) |
C2 | 0.0254 (5) | 0.0473 (7) | 0.0180 (5) | −0.0033 (5) | 0.0027 (4) | −0.0017 (4) |
C3 | 0.0230 (5) | 0.0250 (5) | 0.0313 (5) | −0.0066 (4) | 0.0053 (4) | −0.0039 (4) |
C4 | 0.0263 (5) | 0.0373 (6) | 0.0229 (5) | 0.0019 (4) | 0.0102 (4) | −0.0010 (4) |
C5 | 0.0340 (6) | 0.0226 (5) | 0.0245 (5) | 0.0009 (4) | −0.0016 (4) | −0.0064 (4) |
C6 | 0.0183 (4) | 0.0243 (5) | 0.0240 (5) | −0.0032 (3) | 0.0043 (4) | −0.0002 (4) |
O1 | 0.0233 (4) | 0.0252 (4) | 0.0408 (5) | 0.0008 (3) | 0.0086 (3) | −0.0054 (3) |
C7 | 0.0309 (6) | 0.0358 (6) | 0.0410 (6) | −0.0085 (5) | 0.0151 (5) | 0.0053 (5) |
C1—N3 | 1.3353 (13) | C3—H3C | 0.9800 |
C1—N2 | 1.3463 (12) | C4—H4A | 0.9800 |
C1—N1 | 1.3541 (13) | C4—H4B | 0.9800 |
N1—C2 | 1.4526 (13) | C4—H4C | 0.9800 |
N1—C3 | 1.4579 (14) | C5—H5A | 0.9800 |
N2—C5 | 1.4568 (13) | C5—H5B | 0.9800 |
N2—C4 | 1.4614 (14) | C5—H5C | 0.9800 |
N3—C6 | 1.3554 (13) | C6—O1 | 1.2325 (13) |
C2—H2A | 0.9800 | C6—C7 | 1.5109 (15) |
C2—H2B | 0.9800 | C7—H7A | 0.9800 |
C2—H2C | 0.9800 | C7—H7B | 0.9800 |
C3—H3A | 0.9800 | C7—H7C | 0.9800 |
C3—H3B | 0.9800 | ||
N3—C1—N2 | 118.62 (9) | N2—C4—H4A | 109.5 |
N3—C1—N1 | 123.11 (9) | N2—C4—H4B | 109.5 |
N2—C1—N1 | 117.99 (9) | H4A—C4—H4B | 109.5 |
C1—N1—C2 | 120.71 (9) | N2—C4—H4C | 109.5 |
C1—N1—C3 | 122.97 (8) | H4A—C4—H4C | 109.5 |
C2—N1—C3 | 113.79 (9) | H4B—C4—H4C | 109.5 |
C1—N2—C5 | 119.86 (9) | N2—C5—H5A | 109.5 |
C1—N2—C4 | 123.83 (9) | N2—C5—H5B | 109.5 |
C5—N2—C4 | 114.53 (9) | H5A—C5—H5B | 109.5 |
C1—N3—C6 | 119.38 (9) | N2—C5—H5C | 109.5 |
N1—C2—H2A | 109.5 | H5A—C5—H5C | 109.5 |
N1—C2—H2B | 109.5 | H5B—C5—H5C | 109.5 |
H2A—C2—H2B | 109.5 | O1—C6—N3 | 126.46 (10) |
N1—C2—H2C | 109.5 | O1—C6—C7 | 119.93 (10) |
H2A—C2—H2C | 109.5 | N3—C6—C7 | 113.51 (10) |
H2B—C2—H2C | 109.5 | C6—C7—H7A | 109.5 |
N1—C3—H3A | 109.5 | C6—C7—H7B | 109.5 |
N1—C3—H3B | 109.5 | H7A—C7—H7B | 109.5 |
H3A—C3—H3B | 109.5 | C6—C7—H7C | 109.5 |
N1—C3—H3C | 109.5 | H7A—C7—H7C | 109.5 |
H3A—C3—H3C | 109.5 | H7B—C7—H7C | 109.5 |
H3B—C3—H3C | 109.5 | ||
N3—C1—N1—C2 | 14.29 (15) | N3—C1—N2—C4 | −147.74 (10) |
N2—C1—N1—C2 | −159.51 (10) | N1—C1—N2—C4 | 26.35 (15) |
N3—C1—N1—C3 | −146.52 (10) | N2—C1—N3—C6 | −136.75 (10) |
N2—C1—N1—C3 | 39.68 (14) | N1—C1—N3—C6 | 49.48 (14) |
N3—C1—N2—C5 | 16.15 (14) | C1—N3—C6—O1 | 17.39 (17) |
N1—C1—N2—C5 | −169.76 (9) | C1—N3—C6—C7 | −166.23 (10) |
D—H···A | D—H | H···A | D···A | 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. |
Experimental details
Crystal data | |
Chemical formula | C7H15N3O |
Mr | 157.22 |
Crystal system, space group | Monoclinic, P21/n |
Temperature (K) | 100 |
a, b, c (Å) | 6.7625 (3), 17.8610 (8), 7.6687 (4) |
β (°) | 103.107 (2) |
V (Å3) | 902.13 (7) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.08 |
Crystal size (mm) | 0.22 × 0.18 × 0.16 |
Data collection | |
Diffractometer | Bruker Kappa APEXII Duo |
Absorption correction | – |
No. of measured, independent and observed [I > 2σ(I)] reflections | 17552, 2758, 2396 |
Rint | 0.031 |
(sin θ/λ)max (Å−1) | 0.716 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.046, 0.117, 1.10 |
No. of reflections | 2758 |
No. of parameters | 105 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.29, −0.22 |
Computer programs: APEX2 (Bruker, 2008), SAINT (Bruker, 2008), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), DIAMOND (Brandenburg & Putz, 2005).
D—H···A | D—H | H···A | D···A | D—H···A |
C3—H3B···O1i | 0.98 | 2.60 | 3.4807 (10) | 149.6 |
C5—H5A···N3ii | 0.98 | 2.61 | 3.5456 (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
Brandenburg, K. & Putz, H. (2005). DIAMOND. Crystal Impact GbR, Bonn, Germany. Google Scholar
Bruker (2008). APEX2 and SAINT. Bruker AXS Inc., Madison, Wisconsin, USA. Google Scholar
Kessler, H. & Leibfritz, D. (1970). Tetrahedron, 26, 1805–1820. CrossRef Web of Science Google Scholar
Matsumoto, K. & Rapoport, H. (1968). J. Org. Chem. 33, 552–558. CrossRef CAS Web of Science Google Scholar
Sheldrick, G. M. (2008). Acta Cryst. A64, 112–122. Web of Science CrossRef CAS IUCr Journals Google Scholar
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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).