1,2,3,4-Tetra­hydro­quinolin-7-amine

The title compound, C₉H₁₂N₂, crystallizes with two almost identical mol­ecules in the asymmetric unit. The ring containing the N atom in the tetra­hydro­quinoline system adopts a half-chair conformation. The crystal structure is stabilized by inter­molecular N—H...N and N—H...π hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 113 K
• Mean [sigma](C-C) = 0.004 Å
• R factor = 0.042
• wR factor = 0.093
• Data-to-parameter ratio = 7.9

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT066_ALERT_1_C Predicted and Reported Transmissions Identical .          ?
PLAT089_ALERT_3_C Poor Data / Parameter Ratio (Zmax .LT. 18) .....       7.87
PLAT125_ALERT_4_C No _symmetry_space_group_name_Hall Given .......          ?
PLAT420_ALERT_2_C D-H Without Acceptor       N2     -   H2D    ...          ?
PLAT420_ALERT_2_C D-H Without Acceptor       N4     -   H4B    ...          ?
PLAT481_ALERT_4_C Long D...A H-Bond Reported N4     ..  CG2     ..       4.01 Ang.

Alert level G
REFLT03_ALERT_4_G Please check that the estimate of the number of Friedel pairs is
            correct. If it is not, please give the correct count in the
            _publ_section_exptl_refinement section of the submitted CIF.
           From the CIF: _diffrn_reflns_theta_max           26.36
           From the CIF: _reflns_number_total               1762
           Count of symmetry unique reflns         1767
           Completeness (_total/calc)             99.72%
           TEST3: Check Friedels for noncentro structure
           Estimate of Friedel pairs measured         0
           Fraction of Friedel pairs measured     0.000
           Are heavy atom types Z>Si present         no
PLAT860_ALERT_3_G Note: Number of Least-Squares Restraints .......          1

   0 ALERT level A = In general: serious problem
   0 ALERT level B = Potentially serious problem
   6 ALERT level C = Check and explain
   2 ALERT level G = General alerts; check

   1 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   2 ALERT type 2 Indicator that the structure model may be wrong or deficient
   2 ALERT type 3 Indicator that the structure quality may be low
   3 ALERT type 4 Improvement, methodology, query or suggestion
   0 ALERT type 5 Informative message, check

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S1. Comment

1,2,3,4-Tetrahydroquinolin-7-amine is an important intermediate for the preparation of 7-hydroxy-1,2,3,4-tetrahydroquinoline which is an intermediate useful for the economic manufacture of laser dyes for wavelengths between 540 and 610 nm (Field & Hammond, 1994). The present X-ray crystal structure analysis was undertaken in order to study the stereochemistry and crystal packing of 1,2,3,4-tetrahydroquinolin-7-amine The molecular structure of the title compound is illustrated in Fig. 1. There are two almost identical molecules in the asymmetric unit. The ring containing the nitrigen atom in the tetrahydroquinolin adopts a partical chair conformation. The crystal structure is stabilized by intermolecular N—H···N and N—H···π hydrogen bonds.

Related literature

For related literature, see: Field & Hammond (1994).

S2. Experimental

7-nitro-1, 2, 3, 4-tetrahydroquinoline (0.05 mol, 8.91 g), 80 ml of methanol and 1.5 g of Raney nickel slurry were rinsed with methanol under nitrogen. Addition of a solution of 5.5 ml (0.1 mol) hydrazine hydrate in 10 ml of methanol to the stirred mixture started the reaction. The reaction mixture was heated under reflux to complete the reduction, the catalyst was filtered off through celite and washed with methanol. The filtrate was concentrated in vacuo and reconcentrated twice with toluene to remove water. The residue was crystallized from PE to give 6.95 g of 7-amine-1,2,3,4-tetrahydroquinolin as a white needle solid, suitable for X-ray analysis. 1,2,3,4-tetrahydroquinolin-7-amine was quite sensitive to air, it quickly changed black solid.

S3. Refinement

H atoms were positioned geometrically with C—H = 0.93–0.98 Å and refined using riding model with U_iso (H) = 1.2 U_eq (carrier). H atoms bonded to N were located from difference map and freely refined. Friedel pairs were merged and the absolute structure was arbitrarily assigned.

Computing details

Data collection: CrystalClear (Rigaku/MSC, 2005); cell refinement: CrystalClear (Rigaku/MSC, 2005); data reduction: CrystalClear (Rigaku/MSC, 2005); program(s) used to solve structure: SHELXS97 (Sheldrick, 1997a); program(s) used to refine structure: SHELXL97 (Sheldrick, 1997a); molecular graphics: SHELXTL (Sheldrick, 1997b); software used to prepare material for publication: CrystalStructure (Rigaku/MSC, 2005).

Figures

	Fig. 1. The molecular structure of the title compound, drawn with 30% probability ellipsoids. H atoms are drawn as spheres of arbitrary radius.
	Fig. 2. The crystal structure of the title compound, viewed along the b axis.

1,2,3,4-Tetrahydroquinolin-7-amine

Crystal data

C9H12N2	Dx = 1.214 Mg m^−3
Mr = 148.21	Melting point = 91–93 K
Monoclinic, P21	Mo Kα radiation, λ = 0.71070 Å
a = 8.7642 (15) Å	Cell parameters from 2296 reflections
b = 8.7401 (14) Å	θ = 1.9–27.5°
c = 11.0393 (18) Å	µ = 0.07 mm^−1
β = 106.459 (7)°	T = 113 K
V = 811.0 (2) Å^3	Prism, colorless
Z = 4	0.10 × 0.04 × 0.04 mm
F(000) = 320

Data collection

Rigaku Saturn diffractometer	1762 independent reflections
Radiation source: rotating anode	1586 reflections with I > 2σ(I)
Confocal monochromator	Rint = 0.043
Detector resolution: 7.31 pixels mm^-1	θmax = 26.4°, θmin = 3.0°
ω scans	h = −10→10
Absorption correction: multi-scan (Jacobson, 1998)	k = −10→10
Tmin = 0.993, Tmax = 0.997	l = −13→13
8269 measured reflections

Refinement

Refinement on F^2	Primary atom site location: structure-invariant direct methods
Least-squares matrix: full	Secondary atom site location: difference Fourier map
R[F^2 > 2σ(F^2)] = 0.042	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.093	H atoms treated by a mixture of independent and constrained refinement
S = 1.09	w = 1/[σ^2(Fo^2) + (0.0483P)^2 + 0.0684P] where P = (Fo^2 + 2Fc^2)/3
1762 reflections	(Δ/σ)max < 0.001
224 parameters	Δρmax = 0.15 e Å^−3
1 restraint	Δρmin = −0.18 e Å^−3

Special details

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 (Ų)

	x	y	z	Uiso*/Ueq
N1	0.7907 (2)	0.5321 (2)	0.1189 (2)	0.0251 (5)
N2	1.2746 (3)	0.7827 (2)	0.1012 (2)	0.0268 (5)
N3	0.3190 (2)	0.2353 (3)	0.1461 (2)	0.0244 (5)
N4	0.7647 (3)	−0.0285 (3)	0.0695 (2)	0.0267 (5)
C1	0.6786 (3)	0.4944 (3)	0.1903 (2)	0.0278 (6)
H1A	0.5921	0.4292	0.1385	0.033*
H1B	0.6306	0.5892	0.2123	0.033*
C2	0.7669 (3)	0.4098 (3)	0.3100 (2)	0.0313 (6)
H2A	0.8169	0.3164	0.2879	0.038*
H2B	0.6912	0.3787	0.3571	0.038*
C3	0.8946 (3)	0.5144 (3)	0.3923 (2)	0.0308 (6)
H3A	0.8432	0.5951	0.4300	0.037*
H3B	0.9647	0.4540	0.4620	0.037*
C4	0.9940 (3)	0.5883 (3)	0.3161 (2)	0.0227 (5)
C5	0.9367 (3)	0.5982 (3)	0.1844 (2)	0.0208 (5)
C6	1.0290 (3)	0.6669 (3)	0.1147 (2)	0.0216 (5)
H6	0.9884	0.6736	0.0254	0.026*
C7	1.1788 (3)	0.7255 (3)	0.1737 (2)	0.0229 (5)
C8	1.2358 (3)	0.7169 (3)	0.3057 (2)	0.0259 (6)
H8	1.3378	0.7567	0.3481	0.031*
C9	1.1429 (3)	0.6501 (3)	0.3738 (2)	0.0266 (6)
H9	1.1824	0.6465	0.4633	0.032*
C10	0.2362 (3)	0.2950 (3)	0.2333 (3)	0.0330 (7)
H10A	0.1309	0.3353	0.1853	0.040*
H10B	0.2983	0.3800	0.2831	0.040*
C11	0.2152 (3)	0.1690 (4)	0.3212 (3)	0.0356 (7)
H11A	0.1514	0.0849	0.2714	0.043*
H11B	0.1574	0.2092	0.3796	0.043*
C12	0.3775 (3)	0.1080 (3)	0.3969 (2)	0.0281 (6)
H12A	0.4321	0.1861	0.4591	0.034*
H12B	0.3626	0.0154	0.4439	0.034*
C13	0.4798 (3)	0.0691 (3)	0.3116 (2)	0.0219 (5)
C14	0.4495 (3)	0.1397 (3)	0.1925 (2)	0.0209 (5)
C15	0.5473 (3)	0.1068 (3)	0.1147 (2)	0.0201 (5)
H15	0.5266	0.1549	0.0346	0.024*
C16	0.6734 (3)	0.0052 (3)	0.1529 (2)	0.0223 (5)
C17	0.7039 (3)	−0.0655 (3)	0.2708 (2)	0.0263 (6)
H17	0.7899	−0.1352	0.2984	0.032*
C18	0.6071 (3)	−0.0325 (3)	0.3470 (2)	0.0243 (5)
H18	0.6284	−0.0814	0.4269	0.029*
H1	0.749 (3)	0.574 (3)	0.042 (2)	0.023 (7)*
H3	0.323 (3)	0.297 (3)	0.080 (3)	0.032 (8)*
H2C	1.218 (3)	0.832 (4)	0.031 (3)	0.037 (8)*
H2D	1.360 (3)	0.841 (4)	0.147 (3)	0.039 (8)*
H4A	0.769 (3)	0.048 (4)	0.015 (3)	0.041 (9)*
H4B	0.866 (4)	−0.066 (4)	0.107 (3)	0.048 (9)*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
N1	0.0245 (10)	0.0299 (13)	0.0195 (11)	−0.0025 (9)	0.0039 (8)	−0.0003 (10)
N2	0.0271 (11)	0.0245 (13)	0.0289 (13)	−0.0037 (9)	0.0084 (9)	0.0005 (10)
N3	0.0270 (11)	0.0248 (12)	0.0234 (11)	0.0066 (9)	0.0104 (9)	0.0049 (10)
N4	0.0248 (11)	0.0268 (13)	0.0303 (12)	−0.0002 (9)	0.0109 (9)	−0.0055 (11)
C1	0.0248 (12)	0.0271 (15)	0.0326 (14)	−0.0044 (11)	0.0097 (10)	−0.0008 (12)
C2	0.0334 (13)	0.0317 (15)	0.0310 (15)	−0.0051 (12)	0.0125 (11)	0.0009 (13)
C3	0.0364 (14)	0.0321 (15)	0.0251 (14)	−0.0082 (12)	0.0103 (11)	0.0006 (12)
C4	0.0270 (12)	0.0217 (13)	0.0199 (12)	0.0029 (10)	0.0073 (9)	0.0004 (10)
C5	0.0221 (11)	0.0159 (12)	0.0238 (12)	0.0037 (10)	0.0055 (9)	−0.0023 (10)
C6	0.0241 (11)	0.0209 (13)	0.0186 (11)	0.0038 (10)	0.0043 (9)	−0.0023 (10)
C7	0.0255 (12)	0.0181 (13)	0.0260 (13)	0.0012 (10)	0.0086 (10)	0.0005 (11)
C8	0.0256 (12)	0.0234 (14)	0.0254 (13)	−0.0028 (11)	0.0020 (10)	−0.0032 (11)
C9	0.0325 (14)	0.0256 (15)	0.0194 (12)	0.0025 (11)	0.0038 (10)	−0.0005 (11)
C10	0.0405 (15)	0.0298 (16)	0.0337 (15)	0.0131 (12)	0.0184 (12)	0.0063 (13)
C11	0.0396 (15)	0.0400 (17)	0.0327 (14)	0.0091 (13)	0.0191 (12)	0.0043 (14)
C12	0.0382 (14)	0.0267 (15)	0.0218 (12)	0.0026 (11)	0.0124 (11)	0.0017 (11)
C13	0.0271 (12)	0.0179 (13)	0.0196 (11)	−0.0035 (10)	0.0049 (9)	−0.0021 (10)
C14	0.0208 (11)	0.0166 (13)	0.0240 (12)	−0.0017 (10)	0.0043 (9)	−0.0036 (10)
C15	0.0237 (12)	0.0180 (13)	0.0183 (11)	−0.0030 (10)	0.0054 (9)	0.0003 (10)
C16	0.0226 (11)	0.0173 (12)	0.0264 (13)	−0.0024 (10)	0.0060 (10)	−0.0053 (11)
C17	0.0220 (12)	0.0217 (14)	0.0312 (14)	0.0024 (10)	0.0013 (10)	−0.0019 (12)
C18	0.0284 (12)	0.0220 (13)	0.0191 (11)	−0.0020 (10)	0.0014 (9)	0.0011 (11)

Geometric parameters (Å, º)

N1—C5	1.403 (3)	C6—C7	1.387 (3)
N1—C1	1.461 (3)	C6—H6	0.9500
N1—H1	0.90 (3)	C7—C8	1.402 (3)
N2—C7	1.405 (3)	C8—C9	1.385 (3)
N2—H2C	0.90 (3)	C8—H8	0.9500
N2—H2D	0.93 (3)	C9—H9	0.9500
N3—C14	1.392 (3)	C10—C11	1.513 (4)
N3—C10	1.456 (3)	C10—H10A	0.9900
N3—H3	0.92 (3)	C10—H10B	0.9900
N4—C16	1.411 (3)	C11—C12	1.527 (4)
N4—H4A	0.90 (3)	C11—H11A	0.9900
N4—H4B	0.92 (3)	C11—H11B	0.9900
C1—C2	1.520 (4)	C12—C13	1.512 (3)
C1—H1A	0.9900	C12—H12A	0.9900
C1—H1B	0.9900	C12—H12B	0.9900
C2—C3	1.529 (4)	C13—C18	1.393 (3)
C2—H2A	0.9900	C13—C14	1.407 (3)
C2—H2B	0.9900	C14—C15	1.404 (3)
C3—C4	1.516 (3)	C15—C16	1.387 (3)
C3—H3A	0.9900	C15—H15	0.9500
C3—H3B	0.9900	C16—C17	1.397 (3)
C4—C9	1.389 (3)	C17—C18	1.383 (3)
C4—C5	1.400 (3)	C17—H17	0.9500
C5—C6	1.401 (3)	C18—H18	0.9500
C5—N1—C1	118.0 (2)	C9—C8—C7	119.7 (2)
C5—N1—H1	112.7 (16)	C9—C8—H8	120.1
C1—N1—H1	116.1 (16)	C7—C8—H8	120.1
C7—N2—H2C	112.6 (17)	C8—C9—C4	122.4 (2)
C7—N2—H2D	113.5 (16)	C8—C9—H9	118.8
H2C—N2—H2D	112 (3)	C4—C9—H9	118.8
C14—N3—C10	118.9 (2)	N3—C10—C11	109.7 (2)
C14—N3—H3	115.7 (16)	N3—C10—H10A	109.7
C10—N3—H3	117.0 (17)	C11—C10—H10A	109.7
C16—N4—H4A	114.3 (19)	N3—C10—H10B	109.7
C16—N4—H4B	115.7 (17)	C11—C10—H10B	109.7
H4A—N4—H4B	110 (3)	H10A—C10—H10B	108.2
N1—C1—C2	108.92 (19)	C10—C11—C12	109.9 (2)
N1—C1—H1A	109.9	C10—C11—H11A	109.7
C2—C1—H1A	109.9	C12—C11—H11A	109.7
N1—C1—H1B	109.9	C10—C11—H11B	109.7
C2—C1—H1B	109.9	C12—C11—H11B	109.7
H1A—C1—H1B	108.3	H11A—C11—H11B	108.2
C1—C2—C3	109.4 (2)	C13—C12—C11	111.3 (2)
C1—C2—H2A	109.8	C13—C12—H12A	109.4
C3—C2—H2A	109.8	C11—C12—H12A	109.4
C1—C2—H2B	109.8	C13—C12—H12B	109.4
C3—C2—H2B	109.8	C11—C12—H12B	109.4
H2A—C2—H2B	108.2	H12A—C12—H12B	108.0
C4—C3—C2	111.3 (2)	C18—C13—C14	117.7 (2)
C4—C3—H3A	109.4	C18—C13—C12	122.5 (2)
C2—C3—H3A	109.4	C14—C13—C12	119.7 (2)
C4—C3—H3B	109.4	N3—C14—C15	118.6 (2)
C2—C3—H3B	109.4	N3—C14—C13	121.6 (2)
H3A—C3—H3B	108.0	C15—C14—C13	119.7 (2)
C9—C4—C5	117.8 (2)	C16—C15—C14	121.2 (2)
C9—C4—C3	121.6 (2)	C16—C15—H15	119.4
C5—C4—C3	120.6 (2)	C14—C15—H15	119.4
C4—C5—C6	120.3 (2)	C15—C16—C17	119.4 (2)
C4—C5—N1	121.1 (2)	C15—C16—N4	119.1 (2)
C6—C5—N1	118.6 (2)	C17—C16—N4	121.4 (2)
C7—C6—C5	121.2 (2)	C18—C17—C16	119.1 (2)
C7—C6—H6	119.4	C18—C17—H17	120.5
C5—C6—H6	119.4	C16—C17—H17	120.5
C6—C7—C8	118.7 (2)	C17—C18—C13	122.9 (2)
C6—C7—N2	120.2 (2)	C17—C18—H18	118.6
C8—C7—N2	121.1 (2)	C13—C18—H18	118.6
C5—N1—C1—C2	−47.4 (3)	C14—N3—C10—C11	−43.4 (3)
N1—C1—C2—C3	62.4 (3)	N3—C10—C11—C12	60.2 (3)
C1—C2—C3—C4	−48.7 (3)	C10—C11—C12—C13	−50.2 (3)
C2—C3—C4—C9	−160.7 (2)	C11—C12—C13—C18	−158.1 (2)
C2—C3—C4—C5	20.2 (3)	C11—C12—C13—C14	23.4 (3)
C9—C4—C5—C6	0.8 (3)	C10—N3—C14—C15	−167.7 (2)
C3—C4—C5—C6	179.9 (2)	C10—N3—C14—C13	16.0 (3)
C9—C4—C5—N1	177.0 (2)	C18—C13—C14—N3	175.9 (2)
C3—C4—C5—N1	−3.9 (4)	C12—C13—C14—N3	−5.5 (3)
C1—N1—C5—C4	18.2 (3)	C18—C13—C14—C15	−0.3 (3)
C1—N1—C5—C6	−165.5 (2)	C12—C13—C14—C15	178.3 (2)
C4—C5—C6—C7	0.4 (3)	N3—C14—C15—C16	−176.1 (2)
N1—C5—C6—C7	−175.9 (2)	C13—C14—C15—C16	0.2 (3)
C5—C6—C7—C8	−1.0 (4)	C14—C15—C16—C17	−0.1 (3)
C5—C6—C7—N2	174.8 (2)	C14—C15—C16—N4	177.7 (2)
C6—C7—C8—C9	0.3 (4)	C15—C16—C17—C18	0.1 (3)
N2—C7—C8—C9	−175.4 (2)	N4—C16—C17—C18	−177.6 (2)
C7—C8—C9—C4	0.9 (4)	C16—C17—C18—C13	−0.2 (4)
C5—C4—C9—C8	−1.5 (4)	C14—C13—C18—C17	0.4 (3)
C3—C4—C9—C8	179.5 (2)	C12—C13—C18—C17	−178.2 (2)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
N4—H4A···N2^i	0.90 (3)	2.39 (3)	3.271 (3)	164 (2)
N4—H4B···Cg2^i	0.90 (3)	3.195	4.015	149
N2—H2C···N1^ii	0.90 (3)	2.40 (3)	3.194 (3)	147 (2)
N2—H2D···Cg1^iii	0.90 (3)	2.53	3.446	168
N3—H3···N4^iv	0.92 (3)	2.22 (3)	3.078 (3)	156 (2)
N1—H1···N3^iv	0.90 (3)	2.44 (3)	3.323 (3)	167 (2)

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