N-(2-Methylphenyl)-1,2-benzoselenazol-3(2H)-one

In the title Ebselen [systematic name: (2-phenyl-1,2-benzoisoselenazol-3-(2H)-one)] analogue, C14H11NOSe, the benzisoselenazolyl moiety (r.m.s. deviation = 0.0209 Å) is nearly perpendicular to the N-arenyl ring, making a dihedral angle of 78.15 (11)°. In the crystal, molecules are linked by C—H⋯O and Se⋯O interactions into chains along the c-axis direction. The Se⋯O distance [2.733 (3) Å] is longer than that in Ebselen (2.571 (3) Å].


Experimental
Crystal data

Comment
Organoselenium compounds play a very important role in biological and relevant processes. Among them, Ebselen (2phenyl-1, 2-benzoisoselenazol-3-(2H)-one) shows anti-inflammatory, anti-atherosclerotic and cytoprotective properties, and has been used as the most active mimic of GPx (glutathione peroxidase). In the past decade, a number of Ebselen analogues were synthesized and their pharmacological activities were thoroughly studied toward a better understanding of the pharmacology of Ebselen. Furthermore, structurally well defined Ebselen analogues with substituents on N-phenyl ring are still rare. Mugesh and co-workers reported several of this kind of Ebselen analogues (Mugesh and Singh, 2000;Mugesh et al., 2001aMugesh et al., , 2001b which exhibited much higher GPx catalytic activity than that of Ebselen when GSH was used as the co-substrate. The molecular structure of the title compound is shown in Fig.1. The molecules in the crystal are linked by C-H···O (C2-H2···O[1/2+x,3/2-y,1/2+z]; H···O: 2.45Å; C···O: 3.132 (4)Å, C-H···O: 130°) and Se···O interactions, forming chains along c. The Se···O distance (2.733 (3) Å) is longer than that in Ebselen (2.571 (3) Å, Dupont et al., 1990). The ninemembered benzisoselenazolyl group, which is similar as that of Ebselen, lies on a plane (r.m.s.d. = 0.0209). The dihedral angle between the planes of benzisoselenazolyl group and the N-arenyl ring is 78.15 (11)°, which is much wider than that in Ebselen (33.39 (13)°). The five-membered isoselenazolyl ring is severely strained at the Se atom, the bond length of Se

Experimental
A solution of 2-(chloroseleno)benzoyl chloride (1.27 g, 5 mmol) in dry acetonitrile (25 ml) was added (dropwise and at room temperature ) to a solution of 2-methylaniline (0.536 g, 5 mmol) and triethylamine in dry acetonitrile (15 ml) while stirring during 30 min. The reaction mixture was then further stirred at room temperature for about 5 h and the solvent was evaporated in vacuo. The precipitate was filtered off and dried to obtain a yellow solid that was purified in an active neutral alumina column, by using ethyl acetate and chloroform (1:2) as eluent. The resulting yellow compound was recrystallized to obtain yellow blocks for X-ray diffraction analysis. Yield, 79%.

Refinement
Crystal data, data collection and structure refinement details are summarized in Table 1. All H atoms were positioned geometrically(C-H = 0.93-0.96 Å), and refined as riding with U iso (H) = 1.2U eq of the adjacent carbon atom (1.5U eq for methyl H atoms).

Figure 1
The molecular structure, showing the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. H atoms have been omitted for clarity. Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 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 (Å 2 )
x y z U iso */U eq Se 1.09550 (