organic compounds
2-(1H-Indol-3-yl)-4,4,5,5-tetramethylimidazolidine-1-oxyl 3-oxide
aDepartment of Chemistry, School of Pharmacy, Fourth Military Medical University, Changle West Road 17, 710032 Xi-An, People's Republic of China
*Correspondence e-mail: xiaoli_sun@yahoo.cn
In the title compound, C15H18N3O2, the plane of the indole ring system is twisted with respect to the plane of the nitronyl nitroxide moiety, exhibiting a dihedral angle of 21.61 (6)°. The crystal packing is stabilized by N—H⋯O hydrogen bonds and weak C—H⋯O interactions.
Related literature
For the preparation of nitronyl et al. (1974). For their biological activity, see: Soule et al. (2007) and their coordination properties, see: Masuda et al. (2009). For related structures, see: Iqbal et al. (2009); Qin et al. (2009); Tanaka et al. (2007).
see: UllmanExperimental
Crystal data
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Refinement
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Data collection: APEX2 (Bruker, 2007); cell SAINT (Bruker, 2007); data reduction: SAINT; program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97 and PLATON (Spek, 2009).
Supporting information
https://doi.org/10.1107/S1600536810002175/fl2283sup1.cif
contains datablocks I, global. DOI:Structure factors: contains datablock I. DOI: https://doi.org/10.1107/S1600536810002175/fl2283Isup2.hkl
2,3-Dimethyl-2,3-bis(hydroxylamino) butane (1.48 g, 10.0 mmol) and 1H-indoline-3-carbaldehyde (1.47 g, 10.0 mmol) were dissolved in methanol. The reaction was stirred for 15 h at reflux temperature, then cooled to room temperature and filtered. The resulting white powder was washed by methanol and suspended in a mixed solution of dichloromethane (30.0 ml) and water (30.0 ml). Then the reaction mixture was added to an aqueous solution of NaIO4 and stirred for 15 min in an ice bath to give a blue solution. The aqueous phase was extracted with CH2Cl2 and the organic layer was combined and dried over MgSO4. Then the solvent was removed to give a dark blue residue which was purified by flash
with the elution of n-hexane/ ethyl acetate (1:3) to yield the title compound (I) as a dark blue powder. Single crystals of (I) were obtained from a mixed solution of n-heptane and dichloromethane (the ratio of volume is 1 to 1).In the structure, all the H atoms were discernible in the difference Fourier maps. However, they were constrained by riding model approximation. C—Hmethyl=0.96 Å; C—Haryl=0.93 Å; UisoHmethyl and UisoHaryl are 1.5 U eq(C) and 1.2 U eq (C), respectively. Since it was not possible to obtain information on the handedness of the molecule from the experimental data the Friedel euivalents were merged before the final cycles of refinement.
Nitronyl
stable organic radicals, that were originally synthesized more than 30 years ago (Ullman et al.1974), have recently received considerable attention (Iqbal et al. 2009; Qin et al. 2009; Tanaka et al. 2007) because of their biological properities as anticancer, antiradiation and antioxidation (Soule et al., 2007). The title compound itself can be used to form coordination compounds with many metal cations, such as Mn2+, Cu2+ and Ni2+ leading to some interesting magentic materials (Masuda, et al., 2009). The molecular structure of the title compound is shown in Fig1. The indole moiety and the nitronyl nitroxide ring are twisted with respect to each other making a dihedral angle of 21.6 (6)°. One of the oxygen atoms (O2) of the nitronyl nitroxide moietie acts as an acceptor in a hydrogen bond from the N—H group of an adjacent molecule and both oxygens (O1 and O2) are acceptors in weak C-H···O intermolecular interactions that help stabilize the crystal packing (Table 1).For of preparation nitronyl
see: Ullman et al. (1974). For their biological activity, see: Soule et al. (2007) and for theircoordination properties, see: Masuda et al. (2009). For related structures, see: Iqbal et al. (2009); Qin et al. (2009); Tanaka et al. (2007).Data collection: APEX2 (Bruker, 2007); cell
SAINT (Bruker, 2007); data reduction: SAINT (Bruker, 2007); program(s) used to solve structure: SHELXS97 (Sheldrick, 2008); program(s) used to refine structure: SHELXL97 (Sheldrick, 2008); molecular graphics: ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 1998); software used to prepare material for publication: SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).Fig. 1. Molecular structure of the title compound (I), showing the atom labeling scheme. Displacement ellipsoids are drawn at the 30% probability level. |
C15H18N3O2 | F(000) = 580 |
Mr = 272.32 | Dx = 1.289 Mg m−3 |
Orthorhombic, Pca21 | Mo Kα radiation, λ = 0.71073 Å |
Hall symbol: P 2c -2ac | Cell parameters from 2598 reflections |
a = 15.0810 (15) Å | θ = 2.7–24.4° |
b = 8.7700 (8) Å | µ = 0.09 mm−1 |
c = 10.6108 (10) Å | T = 296 K |
V = 1403.4 (2) Å3 | Block, blue |
Z = 4 | 0.37 × 0.29 × 0.18 mm |
Bruker APEXII CCD area-detector diffractometer | 1323 independent reflections |
Radiation source: fine-focus sealed tube | 1208 reflections with I > 2σ(I) |
Graphite monochromator | Rint = 0.023 |
phi and ω scans | θmax = 25.1°, θmin = 2.3° |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | h = −14→17 |
Tmin = 0.968, Tmax = 0.984 | k = −8→10 |
6651 measured reflections | l = −12→12 |
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)] = 0.025 | H-atom parameters constrained |
wR(F2) = 0.067 | w = 1/[σ2(Fo2) + (0.0394P)2 + 0.1053P] where P = (Fo2 + 2Fc2)/3 |
S = 1.06 | (Δ/σ)max < 0.001 |
1323 reflections | Δρmax = 0.13 e Å−3 |
186 parameters | Δρmin = −0.09 e Å−3 |
1 restraint | Extinction correction: SHELXL97 (Sheldrick, 2008), Fc*=kFc[1+0.001xFc2λ3/sin(2θ)]-1/4 |
Primary atom site location: structure-invariant direct methods | Extinction coefficient: 0.0146 (19) |
C15H18N3O2 | V = 1403.4 (2) Å3 |
Mr = 272.32 | Z = 4 |
Orthorhombic, Pca21 | Mo Kα radiation |
a = 15.0810 (15) Å | µ = 0.09 mm−1 |
b = 8.7700 (8) Å | T = 296 K |
c = 10.6108 (10) Å | 0.37 × 0.29 × 0.18 mm |
Bruker APEXII CCD area-detector diffractometer | 1323 independent reflections |
Absorption correction: multi-scan (SADABS; Bruker, 2007) | 1208 reflections with I > 2σ(I) |
Tmin = 0.968, Tmax = 0.984 | Rint = 0.023 |
6651 measured reflections |
R[F2 > 2σ(F2)] = 0.025 | 1 restraint |
wR(F2) = 0.067 | H-atom parameters constrained |
S = 1.06 | Δρmax = 0.13 e Å−3 |
1323 reflections | Δρmin = −0.09 e Å−3 |
186 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. we could not determine the absolute configuration,because there is no atom heavier than Si in the molecular |
x | y | z | Uiso*/Ueq | ||
N1 | −0.01319 (14) | 1.0261 (2) | 0.9413 (2) | 0.0605 (5) | |
H1 | −0.0087 | 1.0928 | 1.0004 | 0.073* | |
N2 | 0.11909 (10) | 0.60749 (18) | 0.83997 (15) | 0.0393 (4) | |
N3 | 0.05128 (10) | 0.62465 (17) | 0.65920 (15) | 0.0381 (4) | |
O1 | 0.14925 (11) | 0.64081 (18) | 0.94892 (14) | 0.0579 (4) | |
O2 | 0.01465 (11) | 0.68277 (17) | 0.56075 (14) | 0.0545 (4) | |
C1 | −0.08282 (15) | 1.0156 (2) | 0.8579 (2) | 0.0534 (6) | |
C2 | −0.16017 (18) | 1.1028 (3) | 0.8506 (3) | 0.0731 (8) | |
H2 | −0.1707 | 1.1825 | 0.9064 | 0.088* | |
C3 | −0.21965 (16) | 1.0666 (3) | 0.7587 (4) | 0.0795 (9) | |
H3 | −0.2715 | 1.1234 | 0.7516 | 0.095* | |
C4 | −0.20480 (15) | 0.9465 (3) | 0.6750 (3) | 0.0692 (7) | |
H4 | −0.2463 | 0.9255 | 0.6126 | 0.083* | |
C5 | −0.12892 (14) | 0.8583 (2) | 0.6839 (2) | 0.0529 (6) | |
H5 | −0.1201 | 0.7769 | 0.6292 | 0.063* | |
C6 | −0.06560 (13) | 0.8930 (2) | 0.7760 (2) | 0.0442 (5) | |
C7 | 0.01895 (13) | 0.8304 (2) | 0.81520 (18) | 0.0407 (5) | |
C8 | 0.04679 (15) | 0.9165 (2) | 0.9167 (2) | 0.0515 (5) | |
H8 | 0.0991 | 0.9010 | 0.9614 | 0.062* | |
C9 | 0.06218 (12) | 0.6932 (2) | 0.77161 (18) | 0.0363 (4) | |
C10 | 0.15347 (12) | 0.4734 (2) | 0.76668 (19) | 0.0385 (4) | |
C11 | 0.24518 (16) | 0.5183 (2) | 0.7176 (2) | 0.0523 (5) | |
H11A | 0.2395 | 0.6018 | 0.6597 | 0.079* | |
H11B | 0.2715 | 0.4328 | 0.6752 | 0.079* | |
H11C | 0.2821 | 0.5483 | 0.7870 | 0.079* | |
C12 | 0.15962 (15) | 0.3356 (2) | 0.8531 (2) | 0.0516 (5) | |
H12A | 0.2043 | 0.3532 | 0.9158 | 0.077* | |
H12B | 0.1749 | 0.2471 | 0.8045 | 0.077* | |
H12C | 0.1035 | 0.3195 | 0.8936 | 0.077* | |
C13 | 0.08199 (13) | 0.4624 (2) | 0.66190 (19) | 0.0381 (4) | |
C14 | 0.00154 (14) | 0.3668 (2) | 0.6989 (2) | 0.0516 (5) | |
H14A | −0.0183 | 0.3965 | 0.7813 | 0.077* | |
H14B | 0.0176 | 0.2609 | 0.6997 | 0.077* | |
H14C | −0.0453 | 0.3829 | 0.6391 | 0.077* | |
C15 | 0.11578 (16) | 0.4160 (3) | 0.5331 (2) | 0.0556 (6) | |
H15A | 0.0674 | 0.4150 | 0.4743 | 0.083* | |
H15B | 0.1415 | 0.3161 | 0.5379 | 0.083* | |
H15C | 0.1598 | 0.4876 | 0.5054 | 0.083* |
U11 | U22 | U33 | U12 | U13 | U23 | |
N1 | 0.0810 (13) | 0.0386 (10) | 0.0620 (12) | 0.0000 (9) | 0.0137 (11) | −0.0174 (10) |
N2 | 0.0440 (9) | 0.0423 (8) | 0.0315 (8) | −0.0009 (7) | 0.0003 (7) | −0.0031 (7) |
N3 | 0.0481 (9) | 0.0330 (8) | 0.0333 (8) | 0.0030 (7) | −0.0032 (7) | 0.0023 (7) |
O1 | 0.0670 (9) | 0.0679 (10) | 0.0389 (8) | 0.0047 (7) | −0.0128 (7) | −0.0112 (8) |
O2 | 0.0774 (10) | 0.0452 (8) | 0.0407 (8) | 0.0126 (7) | −0.0113 (8) | 0.0051 (6) |
C1 | 0.0613 (13) | 0.0344 (11) | 0.0644 (15) | −0.0023 (9) | 0.0182 (12) | −0.0009 (10) |
C2 | 0.0771 (18) | 0.0385 (12) | 0.104 (2) | 0.0098 (11) | 0.0325 (17) | 0.0013 (14) |
C3 | 0.0534 (14) | 0.0547 (14) | 0.130 (3) | 0.0105 (11) | 0.0192 (18) | 0.0178 (18) |
C4 | 0.0492 (13) | 0.0600 (14) | 0.098 (2) | −0.0007 (11) | 0.0023 (14) | 0.0130 (15) |
C5 | 0.0485 (11) | 0.0439 (11) | 0.0663 (15) | −0.0032 (9) | 0.0053 (11) | 0.0049 (11) |
C6 | 0.0487 (10) | 0.0304 (10) | 0.0535 (12) | −0.0032 (8) | 0.0117 (10) | 0.0034 (9) |
C7 | 0.0485 (11) | 0.0329 (10) | 0.0406 (11) | −0.0040 (8) | 0.0070 (8) | −0.0021 (8) |
C8 | 0.0614 (13) | 0.0411 (11) | 0.0520 (13) | −0.0036 (10) | 0.0062 (11) | −0.0070 (10) |
C9 | 0.0405 (9) | 0.0333 (9) | 0.0351 (10) | −0.0032 (8) | 0.0014 (8) | 0.0005 (9) |
C10 | 0.0418 (10) | 0.0375 (10) | 0.0363 (9) | 0.0025 (7) | 0.0029 (8) | 0.0009 (9) |
C11 | 0.0440 (10) | 0.0571 (12) | 0.0560 (12) | −0.0003 (10) | 0.0081 (10) | −0.0009 (12) |
C12 | 0.0584 (13) | 0.0488 (12) | 0.0474 (12) | 0.0065 (9) | −0.0017 (10) | 0.0091 (11) |
C13 | 0.0464 (10) | 0.0323 (9) | 0.0357 (9) | 0.0031 (8) | 0.0015 (8) | −0.0008 (8) |
C14 | 0.0540 (11) | 0.0415 (11) | 0.0592 (13) | −0.0070 (9) | −0.0065 (11) | −0.0003 (10) |
C15 | 0.0734 (15) | 0.0521 (12) | 0.0412 (12) | 0.0127 (11) | 0.0007 (11) | −0.0085 (10) |
N1—C8 | 1.346 (3) | C7—C8 | 1.381 (3) |
N1—C1 | 1.377 (3) | C7—C9 | 1.444 (3) |
N1—H1 | 0.8600 | C8—H8 | 0.9300 |
N2—O1 | 1.276 (2) | C10—C12 | 1.519 (3) |
N2—C9 | 1.352 (2) | C10—C11 | 1.529 (3) |
N2—C10 | 1.502 (2) | C10—C13 | 1.552 (3) |
N3—O2 | 1.287 (2) | C11—H11A | 0.9600 |
N3—C9 | 1.346 (2) | C11—H11B | 0.9600 |
N3—C13 | 1.496 (2) | C11—H11C | 0.9600 |
C1—C2 | 1.397 (3) | C12—H12A | 0.9600 |
C1—C6 | 1.407 (3) | C12—H12B | 0.9600 |
C2—C3 | 1.362 (5) | C12—H12C | 0.9600 |
C2—H2 | 0.9300 | C13—C15 | 1.515 (3) |
C3—C4 | 1.396 (4) | C13—C14 | 1.526 (3) |
C3—H3 | 0.9300 | C14—H14A | 0.9600 |
C4—C5 | 1.384 (3) | C14—H14B | 0.9600 |
C4—H4 | 0.9300 | C14—H14C | 0.9600 |
C5—C6 | 1.400 (3) | C15—H15A | 0.9600 |
C5—H5 | 0.9300 | C15—H15B | 0.9600 |
C6—C7 | 1.449 (3) | C15—H15C | 0.9600 |
C8—N1—C1 | 109.91 (19) | N2—C10—C12 | 109.33 (16) |
C8—N1—H1 | 125.0 | N2—C10—C11 | 106.68 (15) |
C1—N1—H1 | 125.0 | C12—C10—C11 | 110.80 (17) |
O1—N2—C9 | 125.79 (16) | N2—C10—C13 | 100.34 (14) |
O1—N2—C10 | 121.68 (16) | C12—C10—C13 | 115.19 (16) |
C9—N2—C10 | 112.14 (16) | C11—C10—C13 | 113.58 (17) |
O2—N3—C9 | 126.49 (15) | C10—C11—H11A | 109.5 |
O2—N3—C13 | 121.66 (15) | C10—C11—H11B | 109.5 |
C9—N3—C13 | 111.73 (15) | H11A—C11—H11B | 109.5 |
N1—C1—C2 | 129.5 (2) | C10—C11—H11C | 109.5 |
N1—C1—C6 | 107.89 (19) | H11A—C11—H11C | 109.5 |
C2—C1—C6 | 122.6 (3) | H11B—C11—H11C | 109.5 |
C3—C2—C1 | 117.5 (3) | C10—C12—H12A | 109.5 |
C3—C2—H2 | 121.2 | C10—C12—H12B | 109.5 |
C1—C2—H2 | 121.2 | H12A—C12—H12B | 109.5 |
C2—C3—C4 | 121.7 (2) | C10—C12—H12C | 109.5 |
C2—C3—H3 | 119.2 | H12A—C12—H12C | 109.5 |
C4—C3—H3 | 119.2 | H12B—C12—H12C | 109.5 |
C5—C4—C3 | 120.7 (3) | N3—C13—C15 | 110.02 (16) |
C5—C4—H4 | 119.6 | N3—C13—C14 | 106.34 (15) |
C3—C4—H4 | 119.6 | C15—C13—C14 | 110.62 (19) |
C4—C5—C6 | 119.3 (2) | N3—C13—C10 | 99.78 (14) |
C4—C5—H5 | 120.3 | C15—C13—C10 | 115.44 (17) |
C6—C5—H5 | 120.3 | C14—C13—C10 | 113.69 (17) |
C5—C6—C1 | 118.12 (19) | C13—C14—H14A | 109.5 |
C5—C6—C7 | 135.90 (19) | C13—C14—H14B | 109.5 |
C1—C6—C7 | 105.97 (19) | H14A—C14—H14B | 109.5 |
C8—C7—C9 | 124.61 (19) | C13—C14—H14C | 109.5 |
C8—C7—C6 | 106.51 (17) | H14A—C14—H14C | 109.5 |
C9—C7—C6 | 128.38 (18) | H14B—C14—H14C | 109.5 |
N1—C8—C7 | 109.7 (2) | C13—C15—H15A | 109.5 |
N1—C8—H8 | 125.1 | C13—C15—H15B | 109.5 |
C7—C8—H8 | 125.1 | H15A—C15—H15B | 109.5 |
N3—C9—N2 | 107.72 (15) | C13—C15—H15C | 109.5 |
N3—C9—C7 | 126.94 (17) | H15A—C15—H15C | 109.5 |
N2—C9—C7 | 125.30 (17) | H15B—C15—H15C | 109.5 |
C8—N1—C1—C2 | 178.2 (2) | C10—N2—C9—C7 | −179.20 (17) |
C8—N1—C1—C6 | −0.2 (2) | C8—C7—C9—N3 | −163.74 (19) |
N1—C1—C2—C3 | −179.1 (2) | C6—C7—C9—N3 | 25.5 (3) |
C6—C1—C2—C3 | −0.9 (4) | C8—C7—C9—N2 | 18.9 (3) |
C1—C2—C3—C4 | 0.4 (4) | C6—C7—C9—N2 | −151.90 (19) |
C2—C3—C4—C5 | 0.8 (4) | O1—N2—C10—C12 | 45.8 (2) |
C3—C4—C5—C6 | −1.6 (4) | C9—N2—C10—C12 | −141.06 (17) |
C4—C5—C6—C1 | 1.1 (3) | O1—N2—C10—C11 | −74.1 (2) |
C4—C5—C6—C7 | 179.4 (2) | C9—N2—C10—C11 | 99.07 (18) |
N1—C1—C6—C5 | 178.64 (19) | O1—N2—C10—C13 | 167.26 (16) |
C2—C1—C6—C5 | 0.1 (3) | C9—N2—C10—C13 | −19.56 (19) |
N1—C1—C6—C7 | −0.1 (2) | O2—N3—C13—C15 | 34.2 (3) |
C2—C1—C6—C7 | −178.6 (2) | C9—N3—C13—C15 | −149.50 (18) |
C5—C6—C7—C8 | −178.0 (2) | O2—N3—C13—C14 | −85.6 (2) |
C1—C6—C7—C8 | 0.4 (2) | C9—N3—C13—C14 | 90.7 (2) |
C5—C6—C7—C9 | −6.0 (4) | O2—N3—C13—C10 | 155.98 (16) |
C1—C6—C7—C9 | 172.47 (19) | C9—N3—C13—C10 | −27.72 (19) |
C1—N1—C8—C7 | 0.5 (2) | N2—C10—C13—N3 | 25.95 (17) |
C9—C7—C8—N1 | −172.98 (19) | C12—C10—C13—N3 | 143.19 (16) |
C6—C7—C8—N1 | −0.5 (2) | C11—C10—C13—N3 | −87.50 (18) |
O2—N3—C9—N2 | −167.34 (17) | N2—C10—C13—C15 | 143.77 (17) |
C13—N3—C9—N2 | 16.6 (2) | C12—C10—C13—C15 | −99.0 (2) |
O2—N3—C9—C7 | 14.9 (3) | C11—C10—C13—C15 | 30.3 (2) |
C13—N3—C9—C7 | −161.20 (17) | N2—C10—C13—C14 | −86.84 (18) |
O1—N2—C9—N3 | 175.82 (17) | C12—C10—C13—C14 | 30.4 (2) |
C10—N2—C9—N3 | 3.0 (2) | C11—C10—C13—C14 | 159.70 (17) |
O1—N2—C9—C7 | −6.4 (3) |
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O2i | 0.86 | 2.07 | 2.8506 (18) | 150 |
C12—H12C···O2ii | 0.96 | 2.51 | 3.434 (2) | 161 |
C14—H14C···O1iii | 0.96 | 2.56 | 3.495 (2) | 164 |
Symmetry codes: (i) −x, −y+2, z+1/2; (ii) −x, −y+1, z+1/2; (iii) −x, −y+1, z−1/2. |
Experimental details
Crystal data | |
Chemical formula | C15H18N3O2 |
Mr | 272.32 |
Crystal system, space group | Orthorhombic, Pca21 |
Temperature (K) | 296 |
a, b, c (Å) | 15.0810 (15), 8.7700 (8), 10.6108 (10) |
V (Å3) | 1403.4 (2) |
Z | 4 |
Radiation type | Mo Kα |
µ (mm−1) | 0.09 |
Crystal size (mm) | 0.37 × 0.29 × 0.18 |
Data collection | |
Diffractometer | Bruker APEXII CCD area-detector |
Absorption correction | Multi-scan (SADABS; Bruker, 2007) |
Tmin, Tmax | 0.968, 0.984 |
No. of measured, independent and observed [I > 2σ(I)] reflections | 6651, 1323, 1208 |
Rint | 0.023 |
(sin θ/λ)max (Å−1) | 0.596 |
Refinement | |
R[F2 > 2σ(F2)], wR(F2), S | 0.025, 0.067, 1.06 |
No. of reflections | 1323 |
No. of parameters | 186 |
No. of restraints | 1 |
H-atom treatment | H-atom parameters constrained |
Δρmax, Δρmin (e Å−3) | 0.13, −0.09 |
Computer programs: APEX2 (Bruker, 2007), SAINT (Bruker, 2007), SHELXS97 (Sheldrick, 2008), ORTEP-3 (Farrugia, 1997) and DIAMOND (Brandenburg, 1998), SHELXL97 (Sheldrick, 2008) and PLATON (Spek, 2009).
D—H···A | D—H | H···A | D···A | D—H···A |
N1—H1···O2i | 0.86 | 2.07 | 2.8506 (18) | 150 |
C12—H12C···O2ii | 0.96 | 2.51 | 3.434 (2) | 161 |
C14—H14C···O1iii | 0.96 | 2.56 | 3.495 (2) | 164 |
Symmetry codes: (i) −x, −y+2, z+1/2; (ii) −x, −y+1, z+1/2; (iii) −x, −y+1, z−1/2. |
Acknowledgements
We thank the Natural Science Foundation of China (grant Nos. 20972189, 20802092, 20802091) for financial support.
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Nitronyl nitroxides, stable organic radicals, that were originally synthesized more than 30 years ago (Ullman et al.1974), have recently received considerable attention (Iqbal et al. 2009; Qin et al. 2009; Tanaka et al. 2007) because of their biological properities as anticancer, antiradiation and antioxidation (Soule et al., 2007). The title compound itself can be used to form coordination compounds with many metal cations, such as Mn2+, Cu2+ and Ni2+ leading to some interesting magentic materials (Masuda, et al., 2009). The molecular structure of the title compound is shown in Fig1. The indole moiety and the nitronyl nitroxide ring are twisted with respect to each other making a dihedral angle of 21.6 (6)°. One of the oxygen atoms (O2) of the nitronyl nitroxide moietie acts as an acceptor in a hydrogen bond from the N—H group of an adjacent molecule and both oxygens (O1 and O2) are acceptors in weak C-H···O intermolecular interactions that help stabilize the crystal packing (Table 1).