3-(3-Aminophenylsulfonyl)aniline

In the title compound, C12H12N2O2S, the aromatic rings are oriented at a dihedral angle of 79.48 (4)°. Intramolecular C—H⋯O hydrogen bonds result in the formation of two five-membered rings with envelope conformations. In the crystal structure, intermolecular N—H⋯O hydrogen bonds link the molecules. π–π Contacts between the benzene rings, [centroid–centroid distance = 4.211 (3) Å] may further stabilize the structure.

In the title compound, C 12 H 12 N 2 O 2 S, the aromatic rings are oriented at a dihedral angle of 79.48 (4) . Intramolecular C-HÁ Á ÁO hydrogen bonds result in the formation of two fivemembered rings with envelope conformations. In the crystal structure, intermolecular N-HÁ Á ÁO hydrogen bonds link the molecules. -Contacts between the benzene rings, [centroid-centroid distance = 4.211 (3) Å ] may further stabilize the structure.
We are grateful to the Islamic Azad University, Shahr-e-Rey Branch, for financial support.

Comment
Aryl sulfones and sulfoxides are interesting functional groups possessing manifold reactivity for conversion to a variety of organosulfur compounds in the fields of drugs and pharmaceuticals (Holland, 1988;Block, 1992). In particular, aryl sulfones have received much attention as powerful anti-HIV-1 agents (McMohan et al., 1993). We report herein the synthesis and crystal structure of the title compound.
In the molecule of the title compound (Fig 1), the bond lengths (Allen et al., 1987) and angles are within normal ranges.
In the crystal structure, intermolecular N-H···O hydrogen bonds (Table 1) link the molecules (Fig. 2), in which they may be effective in the stabilization of the structure. The π-π contact between the phenyl rings, Cg1-Cg1 i [symmetry code: (i) 1 -x, -y, -z, where Cg1 is centroid of the ring A (C1-C6)] may further stabilize the structure, with centroid-centroid distance of 4.211 (3) Å.

Experimental
For the preparation of the title compound, a solution of 3,3'-diaminodiphenyl sulfone (0.52 g, 2.0 mmol) in methanol (10 ml) was added to a solution of pyrazinecarboxylic acid (0.51 g, 4.0 mmol) in methanol (20 ml), and the resulting yellow solution was stirred for 40 min at 313 K. It was left to evaporate slowly at room temperature. After one week, yellow prismatic crystals of the title compound were isolated (yield; 0.45 g, 86.5%).

Refinement
H atoms were positioned geometrically, with N-H = 0.86 Å (for NH 2 ) and C-H = 0.93 Å for aromatic H and constrained to ride on their parent atoms, with U iso (H) = 1.2U eq (C,N). Fig. 1. The molecular structure of the title molecule, with the atom-numbering scheme. Displacement ellipsoids are drawn at the 30% probability level. as those based on F, and R-factors based on ALL data will be even larger.