organic compounds
N-Cyclohexyl-3-methylbenzamidine
aInstitute of Applied Chemistry, Shanxi University, Taiyuan 030006, People's Republic of China
*Correspondence e-mail: sdbai@sxu.edu.cn
The title amidine compound, C14H20N2, prepared by a one-pot reaction, is asymmetric as only one N atom has an alkyl substituent. The terminal cyclohexyl group connected to the amino N atom is located on the other side of the N—C—N skeleton to the 4-methylbenzene ring and has a chair conformation. The dihedral angle between the phenyl ring and the NCN plane is 47.87 (12)°. In the crystal, molecules are linked via N—H⋯N hydrogen bonds, forming chains propagating along the a-axis direction.
Related literature
For reviews of related metal amidinates and their applications in olefin polymerization, see: Edelmann (1994); Barker & Kilner (1994); Collins (2011); Bai et al. (2010); Yang et al. (2013). For a review of neutral see: Coles (2006). For a related synthetic method for see: Wang et al. (2008). For related silyl-linked bis(amidinate) ligands, see: Bai et al. (2006).
Experimental
Crystal data
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Refinement
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Data collection: SMART (Bruker, 2000); cell SAINT (Bruker, 2000); data reduction: SAINT; 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: SHELXL97.
Supporting information
10.1107/S1600536813006272/rk2395sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: 10.1107/S1600536813006272/rk2395Isup2.hkl
Supporting information file. DOI: 10.1107/S1600536813006272/rk2395Isup3.cml
A solution of LiBu (2.2 M, 2.7 ml, 6.0 mmol) in hexane was slowly added into a stirred solution of cyclohexylamine (0.69 ml, 6.0 mmol) in Et2O (ca 30 ml) by syringe at 273 K. The reaction mixture was warmed to room temperature and kept stirring for 3 h. Then m–tolunitrile (0.71 ml, 6.0 mmol) was added by syringe at 273 K. The reaction mixture was warmed to room temperature and kept stirring for 4 h. H2O (0.11 ml, 6.0 mmol) was added by syringe at 273 K. After stirred at room temperature for 4 h, the mixture was filtered and the filtrate was dried in vacuum to remove all volatiles. The residue was recrystallized with CH2Cl2 and gave colourless crystals of the title compound (yield 0.96 g, 74%). 1H NMR (300 MHz, CDCl3): δ = 7.38–7.25 (m, 4H; phenyl), 3.81 (br, 2H; NH), 2.43 (s, 3H; m–MePh), 2.15–1.21 (m, 11H; Cy). 13C NMR (75 MHz, CDCl3): δ = 139.3–123.6 (Ph), 50.4 (m–MePh), 33.8, 26.5, 25.6, 22.0 (Cy). Anal. Calc. for C14H20N2 (216.32): C, 77.73; H, 9.32; N, 12.95%. Found: C, 77.46; H, 9.22; N, 13.04%.
The methyl H atoms were constrained to an ideal geometry, with C—H distances of 0.98Å and Uiso(H) = 1.5Ueq(C), but each group was allowed to rotate freely about its C—C bond. The methylene H atoms were constrained with C—H distances of 0.99Å and Uiso(H) = 1.2Ueq(C). The methine H atom was constrained with C—H distance of 1.00Å and Uiso(H) = 1.2Ueq(C). The phenyl H atoms were placed in geometrically idealized positions and constrained to ride on their parent atoms, with C—H distances in the range 0.95Å and Uiso(H) = 1.2Ueq(C).
The
was omitted in because no any atoms heavy Si.Data collection: SMART (Bruker, 2000); cell
SAINT (Bruker, 2000); data reduction: SAINT (Bruker, 2000); 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: SHELXL97 (Sheldrick, 2008).C14H20N2 | F(000) = 472 |
Mr = 216.32 | Dx = 1.128 Mg m−3 |
Orthorhombic, P212121 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2ac 2ab | Cell parameters from 1347 reflections |
a = 9.064 (2) Å | θ = 2.8–20.0° |
b = 11.417 (3) Å | µ = 0.07 mm−1 |
c = 12.311 (3) Å | T = 200 K |
V = 1274.0 (5) Å3 | Block, colourless |
Z = 4 | 0.30 × 0.25 × 0.20 mm |
Bruker SMART CCD diffractometer | 2244 independent reflections |
Radiation source: fine–focus sealed tube | 1758 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.042 |
ϕ and ω scan | θmax = 25.0°, θmin = 2.4° |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | h = −10→7 |
Tmin = 0.980, Tmax = 0.987 | k = −13→12 |
7147 measured reflections | l = −14→14 |
Refinement on F2 | Secondary atom site location: difference Fourier map |
Least-squares matrix: full | Hydrogen site location: inferred from neighbouring sites |
R[F2 > 2σ(F2)] = 0.040 | H atoms treated by a mixture of independent and constrained refinement |
wR(F2) = 0.098 | w = 1/[σ2(Fo2) + (0.0452P)2 + 0.0788P] where P = (Fo2 + 2Fc2)/3 |
S = 1.02 | (Δ/σ)max < 0.001 |
2244 reflections | Δρmax = 0.15 e Å−3 |
154 parameters | Δρmin = −0.12 e Å−3 |
0 restraints | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.020 (3) |
C14H20N2 | V = 1274.0 (5) Å3 |
Mr = 216.32 | Z = 4 |
Orthorhombic, P212121 | Mo Kα radiation |
a = 9.064 (2) Å | µ = 0.07 mm−1 |
b = 11.417 (3) Å | T = 200 K |
c = 12.311 (3) Å | 0.30 × 0.25 × 0.20 mm |
Bruker SMART CCD diffractometer | 2244 independent reflections |
Absorption correction: multi-scan (SADABS; Sheldrick, 1996) | 1758 reflections with I > 2σ(I) |
Tmin = 0.980, Tmax = 0.987 | Rint = 0.042 |
7147 measured reflections |
R[F2 > 2σ(F2)] = 0.040 | 0 restraints |
wR(F2) = 0.098 | H atoms treated by a mixture of independent and constrained refinement |
S = 1.02 | Δρmax = 0.15 e Å−3 |
2244 reflections | Δρmin = −0.12 e Å−3 |
154 parameters |
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 > 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 | ||
N1 | 0.12298 (18) | 0.22773 (14) | 0.08238 (13) | 0.0434 (4) | |
N2 | −0.08387 (18) | 0.17325 (15) | −0.02421 (15) | 0.0475 (5) | |
C1 | 0.1003 (2) | 0.14588 (16) | 0.17183 (15) | 0.0391 (5) | |
H1B | −0.0079 | 0.1422 | 0.1872 | 0.047* | |
C2 | 0.1528 (2) | 0.02235 (17) | 0.14538 (16) | 0.0502 (6) | |
H2C | 0.0991 | −0.0073 | 0.0810 | 0.060* | |
H2D | 0.2593 | 0.0240 | 0.1277 | 0.060* | |
C3 | 0.1267 (3) | −0.05956 (17) | 0.24111 (18) | 0.0611 (7) | |
H3A | 0.0195 | −0.0656 | 0.2553 | 0.073* | |
H3B | 0.1638 | −0.1387 | 0.2228 | 0.073* | |
C4 | 0.2041 (3) | −0.0156 (2) | 0.34235 (18) | 0.0612 (7) | |
H4A | 0.3122 | −0.0170 | 0.3308 | 0.073* | |
H4B | 0.1809 | −0.0679 | 0.4042 | 0.073* | |
C5 | 0.1552 (3) | 0.10824 (19) | 0.36872 (17) | 0.0612 (6) | |
H5A | 0.2124 | 0.1376 | 0.4316 | 0.073* | |
H5B | 0.0496 | 0.1075 | 0.3894 | 0.073* | |
C6 | 0.1769 (2) | 0.19043 (17) | 0.27290 (16) | 0.0485 (5) | |
H6A | 0.1375 | 0.2687 | 0.2916 | 0.058* | |
H6B | 0.2837 | 0.1989 | 0.2581 | 0.058* | |
C7 | 0.0332 (2) | 0.23343 (16) | −0.00570 (16) | 0.0382 (5) | |
C8 | 0.0761 (2) | 0.32275 (16) | −0.08846 (16) | 0.0387 (5) | |
C9 | 0.1108 (2) | 0.43699 (16) | −0.05829 (17) | 0.0460 (5) | |
H9A | 0.1104 | 0.4587 | 0.0162 | 0.055* | |
C10 | 0.1457 (3) | 0.51857 (19) | −0.13683 (18) | 0.0559 (6) | |
H10A | 0.1683 | 0.5967 | −0.1162 | 0.067* | |
C11 | 0.1480 (3) | 0.48753 (19) | −0.24477 (19) | 0.0578 (6) | |
H11A | 0.1724 | 0.5446 | −0.2980 | 0.069* | |
C12 | 0.1153 (2) | 0.37453 (19) | −0.27700 (17) | 0.0520 (6) | |
C13 | 0.0782 (2) | 0.29362 (17) | −0.19718 (16) | 0.0446 (5) | |
H13A | 0.0536 | 0.2160 | −0.2181 | 0.054* | |
C14 | 0.1184 (3) | 0.3393 (2) | −0.3945 (2) | 0.0864 (9) | |
H14A | 0.0928 | 0.2562 | −0.4010 | 0.130* | |
H14B | 0.2174 | 0.3523 | −0.4240 | 0.130* | |
H14C | 0.0469 | 0.3864 | −0.4352 | 0.130* | |
H2A | −0.098 (2) | 0.1201 (17) | 0.0303 (17) | 0.054 (6)* | |
H1A | 0.213 (2) | 0.2603 (17) | 0.0752 (16) | 0.052 (6)* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0400 (10) | 0.0501 (10) | 0.0401 (9) | −0.0084 (9) | −0.0028 (8) | 0.0139 (8) |
N2 | 0.0419 (10) | 0.0512 (10) | 0.0495 (11) | −0.0071 (9) | −0.0050 (8) | 0.0109 (9) |
C1 | 0.0377 (10) | 0.0413 (11) | 0.0384 (11) | −0.0025 (9) | 0.0019 (9) | 0.0065 (8) |
C2 | 0.0573 (14) | 0.0481 (12) | 0.0451 (13) | 0.0004 (11) | −0.0039 (11) | −0.0022 (10) |
C3 | 0.0705 (17) | 0.0405 (11) | 0.0721 (16) | −0.0032 (12) | −0.0081 (14) | 0.0079 (12) |
C4 | 0.0729 (16) | 0.0571 (14) | 0.0536 (15) | 0.0025 (14) | −0.0025 (13) | 0.0189 (11) |
C5 | 0.0785 (16) | 0.0640 (15) | 0.0410 (13) | 0.0052 (13) | −0.0004 (12) | 0.0068 (11) |
C6 | 0.0565 (13) | 0.0438 (11) | 0.0450 (12) | 0.0025 (11) | −0.0040 (10) | −0.0009 (10) |
C7 | 0.0364 (10) | 0.0379 (11) | 0.0402 (12) | 0.0025 (9) | 0.0009 (9) | 0.0016 (9) |
C8 | 0.0342 (10) | 0.0392 (11) | 0.0427 (12) | 0.0062 (9) | −0.0006 (9) | 0.0042 (9) |
C9 | 0.0502 (13) | 0.0430 (11) | 0.0448 (12) | 0.0024 (10) | −0.0028 (10) | 0.0033 (10) |
C10 | 0.0701 (16) | 0.0387 (11) | 0.0590 (15) | −0.0026 (11) | −0.0040 (12) | 0.0082 (11) |
C11 | 0.0638 (16) | 0.0524 (13) | 0.0570 (15) | −0.0022 (12) | 0.0016 (12) | 0.0212 (12) |
C12 | 0.0552 (14) | 0.0590 (13) | 0.0418 (13) | 0.0052 (12) | 0.0000 (11) | 0.0089 (11) |
C13 | 0.0460 (12) | 0.0448 (11) | 0.0431 (12) | 0.0012 (10) | −0.0011 (9) | 0.0006 (10) |
C14 | 0.123 (2) | 0.0921 (19) | 0.0440 (14) | −0.0059 (19) | 0.0068 (16) | 0.0102 (14) |
N1—C7 | 1.357 (2) | C5—H5B | 0.9900 |
N1—C1 | 1.459 (2) | C6—H6A | 0.9900 |
N1—H1A | 0.90 (2) | C6—H6B | 0.9900 |
N2—C7 | 1.284 (2) | C7—C8 | 1.493 (3) |
N2—H2A | 0.91 (2) | C8—C13 | 1.379 (3) |
C1—C6 | 1.513 (3) | C8—C9 | 1.392 (3) |
C1—C2 | 1.524 (3) | C9—C10 | 1.379 (3) |
C1—H1B | 1.0000 | C9—H9A | 0.9500 |
C2—C3 | 1.523 (3) | C10—C11 | 1.375 (3) |
C2—H2C | 0.9900 | C10—H10A | 0.9500 |
C2—H2D | 0.9900 | C11—C12 | 1.382 (3) |
C3—C4 | 1.516 (3) | C11—H11A | 0.9500 |
C3—H3A | 0.9900 | C12—C13 | 1.390 (3) |
C3—H3B | 0.9900 | C12—C14 | 1.502 (3) |
C4—C5 | 1.517 (3) | C13—H13A | 0.9500 |
C4—H4A | 0.9900 | C14—H14A | 0.9800 |
C4—H4B | 0.9900 | C14—H14B | 0.9800 |
C5—C6 | 1.520 (3) | C14—H14C | 0.9800 |
C5—H5A | 0.9900 | ||
C7—N1—C1 | 123.32 (16) | C1—C6—C5 | 111.80 (17) |
C7—N1—H1A | 116.5 (13) | C1—C6—H6A | 109.3 |
C1—N1—H1A | 117.7 (13) | C5—C6—H6A | 109.3 |
C7—N2—H2A | 110.1 (13) | C1—C6—H6B | 109.3 |
N1—C1—C6 | 109.93 (15) | C5—C6—H6B | 109.3 |
N1—C1—C2 | 112.82 (15) | H6A—C6—H6B | 107.9 |
C6—C1—C2 | 110.11 (16) | N2—C7—N1 | 127.70 (18) |
N1—C1—H1B | 107.9 | N2—C7—C8 | 117.35 (18) |
C6—C1—H1B | 107.9 | N1—C7—C8 | 114.94 (16) |
C2—C1—H1B | 107.9 | C13—C8—C9 | 118.79 (18) |
C3—C2—C1 | 110.77 (16) | C13—C8—C7 | 120.08 (17) |
C3—C2—H2C | 109.5 | C9—C8—C7 | 121.12 (18) |
C1—C2—H2C | 109.5 | C10—C9—C8 | 119.8 (2) |
C3—C2—H2D | 109.5 | C10—C9—H9A | 120.1 |
C1—C2—H2D | 109.5 | C8—C9—H9A | 120.1 |
H2C—C2—H2D | 108.1 | C11—C10—C9 | 120.4 (2) |
C4—C3—C2 | 111.18 (18) | C11—C10—H10A | 119.8 |
C4—C3—H3A | 109.4 | C9—C10—H10A | 119.8 |
C2—C3—H3A | 109.4 | C10—C11—C12 | 121.0 (2) |
C4—C3—H3B | 109.4 | C10—C11—H11A | 119.5 |
C2—C3—H3B | 109.4 | C12—C11—H11A | 119.5 |
H3A—C3—H3B | 108.0 | C11—C12—C13 | 118.0 (2) |
C3—C4—C5 | 110.44 (19) | C11—C12—C14 | 121.5 (2) |
C3—C4—H4A | 109.6 | C13—C12—C14 | 120.5 (2) |
C5—C4—H4A | 109.6 | C8—C13—C12 | 121.95 (19) |
C3—C4—H4B | 109.6 | C8—C13—H13A | 119.0 |
C5—C4—H4B | 109.6 | C12—C13—H13A | 119.0 |
H4A—C4—H4B | 108.1 | C12—C14—H14A | 109.5 |
C4—C5—C6 | 111.80 (18) | C12—C14—H14B | 109.5 |
C4—C5—H5A | 109.3 | H14A—C14—H14B | 109.5 |
C6—C5—H5A | 109.3 | C12—C14—H14C | 109.5 |
C4—C5—H5B | 109.3 | H14A—C14—H14C | 109.5 |
C6—C5—H5B | 109.3 | H14B—C14—H14C | 109.5 |
H5A—C5—H5B | 107.9 |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···N2i | 0.90 (2) | 2.08 (2) | 2.975 (2) | 168.0 (18) |
Symmetry code: (i) x+1/2, −y+1/2, −z. |
Experimental details
Crystal data | |
Chemical formula | C14H20N2 |
Mr | 216.32 |
Crystal system, space group | Orthorhombic, P212121 |
Temperature (K) | 200 |
a, b, c (Å) | 9.064 (2), 11.417 (3), 12.311 (3) |
V (Å3) | 1274.0 (5) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.07 |
Crystal size (mm) | 0.30 × 0.25 × 0.20 |
Data collection | |
Diffractometer | Bruker SMART CCD diffractometer |
Absorption correction | Multi-scan (SADABS; Sheldrick, 1996) |
Tmin, Tmax | 0.980, 0.987 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 7147, 2244, 1758 |
Rint | 0.042 |
(sin θ/λ)max (Å−1) | 0.595 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.040, 0.098, 1.02 |
No. of reflections | 2244 |
No. of parameters | 154 |
H-atom treatment | H atoms treated by a mixture of independent and constrained refinement |
Δρmax, Δρmin (e Å−3) | 0.15, −0.12 |
Computer programs: SMART (Bruker, 2000), SAINT (Bruker, 2000), SHELXS97 (Sheldrick, 2008), SHELXL97 (Sheldrick, 2008), SHELXTL (Sheldrick, 2008).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1A···N2i | 0.90 (2) | 2.08 (2) | 2.975 (2) | 168.0 (18) |
Symmetry code: (i) x+1/2, −y+1/2, −z. |
Acknowledgements
This work was supported by grants from the Natural Science Foundation of China (20702029) and the Natural Science Foundation of Shanxi Province (2008011024).
References
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This is an open-access article distributed under the terms of the Creative Commons Attribution (CC-BY) Licence, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are cited.
The exploration of ancillary ligand systems supporting catalytically active metal centers is a long–standing demand in the coordination chemistry. Amidinates represent an important class in the array comparable to the cyclopentadienyl system (Edelmann, 1994; Barker & Kilner, 1994; Collins, 2011). They are four–electron, monoanionic and N–donor bidentate chelates, demonstrating a great diversity by variation of substituents on the conjugated N—C—N backbone. Their steric and electronic properties are easily tunable to meet therequirements of different metal centers. In the course of extending amidinate chemistry, we explored a synthetic pathway to the silyl–linked bis(amidinate) ligands, [SiMe2{NC(Ph)N(R)}2]2- (Bai et al., 2006). They were applied to synthesize the Group 4 complexes, which were good catalysts for ethylene polymerization (Bai et al., 2010; Yang et al., 2013). Amidines are convenient precursors for both monoanionic amidinate ligands and bianionic ansa–bis(amidinate) ligands (Coles, 2006). Some amidines could be prepared by Yb complex catalyzed addtion reactions of aromatic amines and nitriles (Wang et al., 2008). Here, the synthesis and crystal structure of a new amidine will be described.
The title compound I was prepared by a one–pot reaction of cyclohexylamine, LiBu, m–tolunitrile and H2O. The intermediate process involved an addition reaction of lithium amide and nitrile to yield lithium monoamidinate. The suitable for X–ray investigation single–crystal of the title compound was obtained by recrystallization in CH2Cl2. Its molecular structure is shown in Fig. 1. Two N atoms connect the central C atom in different lengths of 1.357 (2)Å and 1.284 (2)Å, composing the characteristic N—C—N skeleton for amidine species. The terminal cyclohexyl with chair–like configuration connects the amino N atom. The phenyl group is attached to the central C atom. The angle between the phenyl plane and the [NCN] plane is 47.87 (12)°. Cyclohexyl and phenyl are in opposite directions. Fig. 2 displays the packing view of compound I. Molecules of I can form the one–dimensional chain extending along a–axis through the intermolecular hydrogen bond. The imino N atom is the acceptor for hydrogen atom. In the chain, every adjacent two molecules have C2 rotation symmetrical relationship with each other and the couple serves as the repeatable unit.