4,4,5,5-Tetra­methyl-2-(4-pyridyl)­imidazolidin-1-oxyl-3-oxide trichloroacetic acid solvate

In the title compound, C₁₂H₁₆N₃O₂·C₂HCl₃O₂, the imidazolidine ring adopts a twist conformation. The crystal structure is stabilized by inter­molecular O—H...N hydrogen bonds.

Key indicators

• Single-crystal X-ray study
• T = 293 K
• Mean [sigma](C-C) = 0.006 Å
• R factor = 0.064
• wR factor = 0.132
• Data-to-parameter ratio = 14.3

checkCIF/PLATON results

No syntax errors found



Alert level C
PLAT340_ALERT_3_C Low Bond Precision on C-C Bonds (x 1000) Ang ...          6
PLAT431_ALERT_2_C Short Inter HL..A Contact  Cl2    ..  O3      ..       3.02 Ang.
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for        C13
PLAT244_ALERT_4_C Low   'Solvent' Ueq as Compared to Neighbors for        C14
PLAT790_ALERT_4_C Centre of Gravity not Within Unit Cell: Resd.  #          1
              C12 H16 N3 O2

Alert level G
PLAT199_ALERT_1_G Check the Reported _cell_measurement_temperature        293 K
PLAT200_ALERT_1_G Check the Reported _diffrn_ambient_temperature .        293 K

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

   2 ALERT type 1 CIF construction/syntax error, inconsistent or missing data
   1 ALERT type 2 Indicator that the structure model may be wrong or deficient
   1 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

Transition metal compounds containing nitroxide radical ligands are of great interest, as these compounds play an important role in molecule-based magnetic materials (Oshio et al., 2002; Vostrikova et al., 2000). In order to investigate the crystal structure of such ligands, the title compound has been synthesized and its crystal structure is reported here.

In the title compound (Fig. 1), the imidazole ring adopts a twist conformation, with atoms C7 and C10 displaced by 0.218 (4) and 0.240 (4) Å respectively on opposite sides of the plane through atoms N2, N3, C6. The dihedral angle between the pyridine and the mean plane of the imidazole ring is 20.31 (27)°. This angle is smaller than that of 25.66 (15)° observed in the unsolvated compound (Zhang et al., 2006). In the crystal structure, an intermolecular hydrogen bonding interaction involving the hydroxyl group of the trichloroacetic acid and the N atom of the pyridine ring is observed (Table 1).

Related literature

For related literature, see: Zhang et al. (2006); Ullman et al. (1972); Oshio et al. (2002); Vostrikova et al. (2000).

S2. Experimental

4,4,5,5-Tetramethyl-2-(4-pyridyl)imidazolin-1-oxyl-3-oxide was prepared according to the published method (Ullman et al., 1972). All chemicals used (reagent grade) were commercially available. 2-(4-Pyridyl)-4,4,5,5-teramethylimidazolin-1-oxyl-3-oxide (0.024 g, 0.1 mmol) was dissolved in ethanol (10 ml). Trichloroacetic acid (0.016 g, 0.1 mmol) was added slowly with stirring. The resulted solution was continuously stirred for about 30 min at room temperature and then filtered. The filtrate was slowly evaporated at room temperature over several days, to give colourless crystals suitable for X-ray analysis.

S3. Refinement

All H atoms were placed at calculated positions and allowed to ride on their parent atoms, with C—H = 0.93–0.96 Å, O—H = 0.82 Å, and with U_iso(H) = 1.5 U_eq(C, O) or 1.2 U_eq(C) for aromatic H atoms.

Computing details

Data collection: CrystalClear (Rigaku, 2005); cell refinement: CrystalClear (Rigaku, 2005); data reduction: CrystalClear (Rigaku, 2005); 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: SHELXTL (Sheldrick, 2008).

Figures

	Fig. 1. The molecular structure of the title compound with the atom-numbering scheme. All hydrogen atoms are omitted except for H4B. Displacement ellipsoids are drawn at the 30% probability level.
	Fig. 2. Packing diagram of the title compound viewed along the b axis. Hydrogen bonds are shown as dashed lines. All hydrogen atoms are omitted except for H4B.

4,4,5,5-Tetramethyl-2-(4-pyridyl)imidazolidin-1-oxyl-3-oxide trichloroacetic acid solvate

Crystal data

C12H16N3O2·C2HCl3O2	F(000) = 820
Mr = 397.66	Dx = 1.497 Mg m^−3
Monoclinic, P21/c	Mo Kα radiation, λ = 0.71073 Å
Hall symbol: -P 2ybc	Cell parameters from 12720 reflections
a = 10.003 (2) Å	θ = 1.0–27.6°
b = 21.036 (4) Å	µ = 0.54 mm^−1
c = 9.2796 (19) Å	T = 293 K
β = 115.33 (3)°	Prism, colourless
V = 1764.9 (7) Å^3	0.20 × 0.20 × 0.20 mm
Z = 4

Data collection

Bruker SMART 1K CCD area-detector diffractometer	3100 independent reflections
Radiation source: fine-focus sealed tube	2041 reflections with I > 2σ(I)
Graphite monochromator	Rint = 0.098
Detector resolution: 8.192 pixels mm^-1	θmax = 25.0°, θmin = 2.5°
thin–slice ω scans	h = −11→11
Absorption correction: multi-scan (CrystalClear; Rigaku, 2005)	k = −25→25
Tmin = 0.895, Tmax = 0.898	l = −11→11
14888 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)] = 0.064	Hydrogen site location: inferred from neighbouring sites
wR(F^2) = 0.132	H-atom parameters constrained
S = 1.06	w = 1/[σ^2(Fo^2) + (0.0424P)^2 + 1.1663P] where P = (Fo^2 + 2Fc^2)/3
3100 reflections	(Δ/σ)max < 0.001
217 parameters	Δρmax = 0.36 e Å^−3
0 restraints	Δρmin = −0.26 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
Cl1	0.23783 (13)	0.11481 (6)	0.16145 (14)	0.0544 (4)
Cl2	0.44021 (13)	0.19710 (5)	0.40583 (14)	0.0544 (4)
Cl3	0.50692 (15)	0.06513 (6)	0.41125 (15)	0.0620 (4)
N3	1.0715 (4)	−0.17317 (15)	0.4059 (4)	0.0378 (8)
O1	0.9245 (3)	−0.03239 (13)	0.2203 (3)	0.0485 (8)
N2	0.9604 (3)	−0.08379 (15)	0.2999 (4)	0.0330 (8)
N1	1.3320 (4)	−0.10702 (18)	0.0574 (4)	0.0431 (9)
C14	0.5057 (4)	0.1426 (2)	0.1725 (5)	0.0396 (10)
C6	1.0677 (4)	−0.12466 (18)	0.3092 (4)	0.0326 (9)
O4	0.5301 (4)	0.09179 (15)	0.1183 (4)	0.0594 (9)
H4B	0.5706	0.0995	0.0598	0.089*
C3	1.1616 (4)	−0.11841 (18)	0.2243 (4)	0.0318 (9)
O2	1.1539 (4)	−0.22208 (15)	0.4388 (4)	0.0679 (10)
O3	0.5285 (4)	0.19655 (16)	0.1466 (4)	0.0700 (10)
C7	0.8677 (4)	−0.11090 (19)	0.3775 (5)	0.0365 (10)
C10	0.9750 (4)	−0.15972 (19)	0.4916 (5)	0.0363 (10)
C5	1.3255 (5)	−0.1617 (2)	0.1249 (5)	0.0456 (11)
H5A	1.3779	−0.1963	0.1134	0.055*
C13	0.4289 (4)	0.13093 (18)	0.2862 (5)	0.0369 (10)
C4	1.2440 (4)	−0.16910 (19)	0.2113 (5)	0.0396 (10)
H4A	1.2443	−0.2077	0.2604	0.048*
C2	1.1702 (5)	−0.0613 (2)	0.1541 (5)	0.0513 (12)
H2A	1.1178	−0.0260	0.1622	0.062*
C12	0.9050 (5)	−0.2207 (2)	0.5118 (6)	0.0630 (14)
H12A	0.8399	−0.2370	0.4090	0.094*
H12B	0.8498	−0.2125	0.5727	0.094*
H12C	0.9809	−0.2514	0.5667	0.094*
C9	0.7334 (5)	−0.1403 (2)	0.2419 (5)	0.0587 (13)
H9A	0.7651	−0.1739	0.1936	0.088*
H9B	0.6828	−0.1084	0.1636	0.088*
H9C	0.6677	−0.1573	0.2832	0.088*
C11	1.0795 (5)	−0.1329 (2)	0.6540 (5)	0.0599 (13)
H11A	1.1223	−0.0940	0.6393	0.090*
H11B	1.1566	−0.1631	0.7088	0.090*
H11C	1.0252	−0.1247	0.7160	0.090*
C1	1.2570 (5)	−0.0571 (2)	0.0721 (5)	0.0537 (13)
H1B	1.2633	−0.0186	0.0262	0.064*
C8	0.8203 (5)	−0.0578 (2)	0.4560 (6)	0.0582 (13)
H8A	0.9059	−0.0399	0.5413	0.087*
H8B	0.7546	−0.0744	0.4976	0.087*
H8C	0.7705	−0.0254	0.3786	0.087*

Atomic displacement parameters (Ų)

	U^11	U^22	U^33	U^12	U^13	U^23
Cl1	0.0439 (7)	0.0609 (8)	0.0638 (8)	−0.0087 (6)	0.0282 (6)	−0.0041 (6)
Cl2	0.0639 (8)	0.0492 (7)	0.0615 (8)	−0.0039 (6)	0.0378 (6)	−0.0122 (6)
Cl3	0.0845 (9)	0.0510 (7)	0.0616 (8)	0.0196 (7)	0.0417 (7)	0.0269 (6)
N3	0.043 (2)	0.0336 (19)	0.043 (2)	0.0057 (17)	0.0234 (17)	0.0060 (16)
O1	0.0541 (19)	0.0439 (18)	0.059 (2)	0.0196 (15)	0.0354 (16)	0.0186 (15)
N2	0.0348 (19)	0.0324 (19)	0.034 (2)	0.0051 (16)	0.0171 (16)	0.0023 (15)
N1	0.042 (2)	0.053 (2)	0.041 (2)	0.0010 (19)	0.0237 (18)	−0.0032 (18)
C14	0.032 (2)	0.052 (3)	0.037 (3)	0.001 (2)	0.016 (2)	0.007 (2)
C6	0.034 (2)	0.034 (2)	0.031 (2)	0.004 (2)	0.0153 (19)	0.0018 (18)
O4	0.071 (2)	0.069 (2)	0.061 (2)	0.0061 (19)	0.0502 (19)	−0.0005 (17)
C3	0.031 (2)	0.036 (2)	0.028 (2)	0.0002 (19)	0.0128 (18)	−0.0016 (17)
O2	0.082 (2)	0.053 (2)	0.093 (3)	0.0336 (19)	0.061 (2)	0.0324 (18)
O3	0.100 (3)	0.055 (2)	0.077 (3)	−0.011 (2)	0.058 (2)	0.0171 (18)
C7	0.030 (2)	0.044 (3)	0.042 (3)	0.001 (2)	0.022 (2)	0.000 (2)
C10	0.036 (2)	0.043 (3)	0.035 (2)	−0.001 (2)	0.021 (2)	0.0006 (19)
C5	0.037 (2)	0.046 (3)	0.061 (3)	0.003 (2)	0.027 (2)	−0.012 (2)
C13	0.041 (2)	0.033 (2)	0.043 (3)	0.0003 (19)	0.024 (2)	0.0059 (19)
C4	0.043 (3)	0.030 (2)	0.052 (3)	0.000 (2)	0.026 (2)	−0.0032 (19)
C2	0.060 (3)	0.049 (3)	0.062 (3)	0.019 (2)	0.043 (3)	0.016 (2)
C12	0.061 (3)	0.057 (3)	0.084 (4)	0.000 (3)	0.044 (3)	0.019 (3)
C9	0.036 (3)	0.079 (4)	0.051 (3)	−0.012 (3)	0.010 (2)	0.005 (3)
C11	0.055 (3)	0.075 (4)	0.045 (3)	0.007 (3)	0.017 (2)	0.002 (2)
C1	0.065 (3)	0.055 (3)	0.058 (3)	0.017 (3)	0.041 (3)	0.023 (2)
C8	0.064 (3)	0.065 (3)	0.064 (3)	0.012 (3)	0.045 (3)	0.007 (3)

Geometric parameters (Å, º)

Cl1—C13	1.793 (4)	C10—C12	1.512 (6)
Cl2—C13	1.754 (4)	C10—C11	1.528 (6)
Cl3—C13	1.760 (4)	C5—C4	1.375 (5)
N3—O2	1.271 (4)	C5—H5A	0.9300
N3—C6	1.349 (5)	C4—H4A	0.9300
N3—C10	1.517 (5)	C2—C1	1.381 (5)
O1—N2	1.272 (4)	C2—H2A	0.9300
N2—C6	1.349 (5)	C12—H12A	0.9600
N2—C7	1.508 (5)	C12—H12B	0.9600
N1—C5	1.324 (5)	C12—H12C	0.9600
N1—C1	1.331 (5)	C9—H9A	0.9600
C14—O3	1.202 (5)	C9—H9B	0.9600
C14—O4	1.249 (5)	C9—H9C	0.9600
C14—C13	1.568 (5)	C11—H11A	0.9600
C6—C3	1.467 (5)	C11—H11B	0.9600
O4—H4B	0.8200	C11—H11C	0.9600
C3—C4	1.385 (5)	C1—H1B	0.9300
C3—C2	1.387 (5)	C8—H8A	0.9600
C7—C8	1.516 (5)	C8—H8B	0.9600
C7—C9	1.525 (6)	C8—H8C	0.9600
C7—C10	1.535 (6)
O2—N3—C6	127.0 (3)	Cl2—C13—Cl1	108.7 (2)
O2—N3—C10	121.2 (3)	Cl3—C13—Cl1	109.1 (2)
C6—N3—C10	111.4 (3)	C5—C4—C3	119.1 (4)
O1—N2—C6	126.8 (3)	C5—C4—H4A	120.4
O1—N2—C7	121.3 (3)	C3—C4—H4A	120.4
C6—N2—C7	111.3 (3)	C1—C2—C3	119.6 (4)
C5—N1—C1	119.5 (3)	C1—C2—H2A	120.2
O3—C14—O4	129.9 (4)	C3—C2—H2A	120.2
O3—C14—C13	118.1 (4)	C10—C12—H12A	109.5
O4—C14—C13	111.9 (4)	C10—C12—H12B	109.5
N3—C6—N2	108.6 (3)	H12A—C12—H12B	109.5
N3—C6—C3	125.7 (3)	C10—C12—H12C	109.5
N2—C6—C3	125.7 (3)	H12A—C12—H12C	109.5
C14—O4—H4B	109.5	H12B—C12—H12C	109.5
C4—C3—C2	117.9 (4)	C7—C9—H9A	109.5
C4—C3—C6	121.3 (3)	C7—C9—H9B	109.5
C2—C3—C6	120.8 (3)	H9A—C9—H9B	109.5
N2—C7—C8	109.4 (3)	C7—C9—H9C	109.5
N2—C7—C9	105.3 (3)	H9A—C9—H9C	109.5
C8—C7—C9	110.4 (4)	H9B—C9—H9C	109.5
N2—C7—C10	101.0 (3)	C10—C11—H11A	109.5
C8—C7—C10	115.6 (3)	C10—C11—H11B	109.5
C9—C7—C10	114.0 (3)	H11A—C11—H11B	109.5
C12—C10—N3	109.8 (3)	C10—C11—H11C	109.5
C12—C10—C11	110.4 (4)	H11A—C11—H11C	109.5
N3—C10—C11	105.4 (3)	H11B—C11—H11C	109.5
C12—C10—C7	115.4 (3)	N1—C1—C2	121.4 (4)
N3—C10—C7	100.2 (3)	N1—C1—H1B	119.3
C11—C10—C7	114.5 (3)	C2—C1—H1B	119.3
N1—C5—C4	122.4 (4)	C7—C8—H8A	109.5
N1—C5—H5A	118.8	C7—C8—H8B	109.5
C4—C5—H5A	118.8	H8A—C8—H8B	109.5
C14—C13—Cl2	112.6 (3)	C7—C8—H8C	109.5
C14—C13—Cl3	111.1 (3)	H8A—C8—H8C	109.5
Cl2—C13—Cl3	108.5 (2)	H8B—C8—H8C	109.5
C14—C13—Cl1	106.8 (3)
O2—N3—C6—N2	177.0 (4)	N2—C7—C10—C12	−143.3 (3)
C10—N3—C6—N2	−9.8 (4)	C8—C7—C10—C12	98.8 (4)
O2—N3—C6—C3	−1.2 (7)	C9—C7—C10—C12	−30.8 (5)
C10—N3—C6—C3	172.0 (3)	N2—C7—C10—N3	−25.4 (3)
O1—N2—C6—N3	179.8 (3)	C8—C7—C10—N3	−143.4 (3)
C7—N2—C6—N3	−9.0 (4)	C9—C7—C10—N3	87.0 (4)
O1—N2—C6—C3	−2.0 (6)	N2—C7—C10—C11	86.8 (4)
C7—N2—C6—C3	169.3 (4)	C8—C7—C10—C11	−31.1 (5)
N3—C6—C3—C4	13.2 (6)	C9—C7—C10—C11	−160.7 (4)
N2—C6—C3—C4	−164.8 (4)	C1—N1—C5—C4	−0.3 (6)
N3—C6—C3—C2	−166.9 (4)	O3—C14—C13—Cl2	−18.8 (5)
N2—C6—C3—C2	15.1 (6)	O4—C14—C13—Cl2	163.2 (3)
O1—N2—C7—C8	−43.0 (5)	O3—C14—C13—Cl3	−140.6 (4)
C6—N2—C7—C8	145.2 (3)	O4—C14—C13—Cl3	41.3 (4)
O1—N2—C7—C9	75.8 (4)	O3—C14—C13—Cl1	100.5 (4)
C6—N2—C7—C9	−96.0 (4)	O4—C14—C13—Cl1	−77.5 (4)
O1—N2—C7—C10	−165.3 (3)	N1—C5—C4—C3	2.2 (6)
C6—N2—C7—C10	22.9 (4)	C2—C3—C4—C5	−2.6 (6)
O2—N3—C10—C12	−41.2 (5)	C6—C3—C4—C5	177.3 (4)
C6—N3—C10—C12	145.1 (4)	C4—C3—C2—C1	1.2 (6)
O2—N3—C10—C11	77.7 (4)	C6—C3—C2—C1	−178.7 (4)
C6—N3—C10—C11	−95.9 (4)	C5—N1—C1—C2	−1.1 (7)
O2—N3—C10—C7	−163.1 (4)	C3—C2—C1—N1	0.7 (7)
C6—N3—C10—C7	23.2 (4)

Hydrogen-bond geometry (Å, º)

D—H···A	D—H	H···A	D···A	D—H···A
O4—H4B···N1^i	0.82	1.75	2.567 (7)	173

Symmetry code: (i) −x+2, −y, −z.