2-(1H-Indol-3-yl)-4,4,5,5-tetra­methyl­imidazolidine-1-oxyl 3-oxide

Hai-Bo Wang; Lin-Lin Jing; Ru Jiang; Peng Liu; Xiao-Li Sun

doi:10.1107/S1600536810002175

. 2010 Jan 23;66(Pt 2):o428. doi: 10.1107/S1600536810002175

2-(1H-Indol-3-yl)-4,4,5,5-tetramethylimidazolidine-1-oxyl 3-oxide

Hai-Bo Wang ^a, Lin-Lin Jing ^a, Ru Jiang ^a, Peng Liu ^a, Xiao-Li Sun ^a,^*

PMCID: PMC2979679 PMID: 21579843

Abstract

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 nitroxides, see: Ullman 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 ▶).

Experimental

Crystal data

C₁₅H₁₈N₃O₂
M _r = 272.32
Orthorhombic,
a = 15.0810 (15) Å
b = 8.7700 (8) Å
c = 10.6108 (10) Å
V = 1403.4 (2) Å³
Z = 4
Mo Kα radiation
μ = 0.09 mm⁻¹
T = 296 K
0.37 × 0.29 × 0.18 mm

Data collection

Bruker APEXII CCD area-detector diffractometer
Absorption correction: multi-scan (SADABS; Bruker, 2007 ▶) T _min = 0.968, T _max = 0.984
6651 measured reflections
1323 independent reflections
1208 reflections with I > 2σ(I)
R _int = 0.023

Refinement

R[F ² > 2σ(F ²)] = 0.025
wR(F ²) = 0.067
S = 1.06
1323 reflections
186 parameters
1 restraint
H-atom parameters constrained
Δρ_max = 0.13 e Å⁻³
Δρ_min = −0.09 e Å⁻³

Data collection: APEX2 (Bruker, 2007 ▶); cell refinement: 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 ▶).

Supplementary Material

Crystal structure: contains datablocks I, global. DOI: 10.1107/S1600536810002175/fl2283sup1.cif

e-66-0o428-sup1.cif^{(19.9KB, cif)}

Structure factors: contains datablocks I. DOI: 10.1107/S1600536810002175/fl2283Isup2.hkl

e-66-0o428-Isup2.hkl^{(65.4KB, hkl)}

Additional supplementary materials: crystallographic information; 3D view; checkCIF report

Table 1. Hydrogen-bond geometry (Å, °).

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

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Symmetry codes: (i) Inline graphic ; (ii) ; (iii) .

Acknowledgments

We thank the Natural Science Foundation of China (grant Nos. 20972189, 20802092, 20802091) for financial support.

supplementary crystallographic information

Comment

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).

Experimental

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 column chromatography 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).