2-[2-(2-Hydroxyethoxy)phenyl]-4,4,5,5-tetramethyl-2-imidazoline-1-oxyl 3-oxide

In the title compound, C15H21N2O4, the nitronyl nitroxide unit displays a twisted conformation. The crystal structure is stabilized by non-classical C—H⋯O and C—H⋯π hydrogen bonds, which build up a three-dimensional network.

In the title compound, C 15 H 21 N 2 O 4 , the nitronyl nitroxide unit displays a twisted conformation. The crystal structure is stabilized by non-classical C-HÁ Á ÁO and C-HÁ Á Á hydrogen bonds, which build up a three-dimensional network.

Comment
Nitronyl nitroxides, firstly synthesized more than 30 years ago, can be used for coordination with many metalcations, such as Mn 2+ , Cu 2+ and Ni 2+ leading to form some molecule based magentic materials (Masuda et al., 2009). They also can react with free radicals such as OH, H 2 O 2 , and O 2 (Blasig et al., 2002) to protect cells from the attack of free radicals. So they have lots of biological properities as anticancer, antiradiation and antioxidation (Qin et al., 2009;Tanaka et al., 2007;Soule et al., 2007).
The crystal structure is stabilized by non-classical intermolecular C-H···O and C-H···π hydrogen bonds (Table 1).
Experimental 2,3-Dimethyl-2,3-bis(hydroxylamino) butane (1.48 g, 10.0 mmol) and 2-(2-hydroxyethoxy)benzaldehyde (1.66 g, 10 mmol) were dissolved in methanol (30.0 ml). The reaction was filtered after stirring for 24 h at room temperature. The resulting white powder was washed by cool methanol and suspended in the solution of dichloromethane (30.0 ml). Then the reaction mixture was added to an aqueous solution of NaIO 4 (30 ml) and stirred for 15 min in an ice bath to give a dark red solution. The aqueous phase was extracted with CH 2 Cl 2 and the organic layer was combined and dried over Na 2 SO 4 . Then the solvent was removed to give a dark red residue which was purified by flash column chromatography with the elution of n-hexane / ethyl acetate (1:3) to yield 1.69 g (57%) of the title compound as a dark red powder. Single crystals of the title compound suitable for X-ray diffraction was recrystallized from hexane / dichloromethane (2:1).

Refinement
In the structure all the H atoms were positioned geometrically and refined with using a riding model: C-H methyl = 0.96Å; C-H methylene = 0.97Å; C-H aryl = 0.93Å and O-H = 0.82Å with U iso (H) = 1.2U eq (C), U iso (H) = 1.5U eq (C methyl ) and