Pi-stacked hydrogen-bonded dimers in 2-(2-nitrophenylaminocarbonyl)benzoic acid, and hydrogen-bonded sheets in orthorhombic and monoclinic polymorphs of 2-(4-nitrophenylaminocarbonyl)benzoic acid.

Molecules of 2-(2-nitrophenylaminocarbonyl)benzoic acid, C(14)H(10)N(2)O(5), are linked into centrosymmetric R(2)(2)(8) dimers by a single O-H.O hydrogen bond [H.O = 1.78 A, O.O = 2.623 (2) A and O-H.O = 178 degrees ] and these dimers are linked into sheets by a single aromatic pi-pi stacking interaction. The isomeric compound 2-(4-nitrophenylaminocarbonyl)benzoic acid crystallizes in two polymorphic forms. In the orthorhombic form (space group P2(1)2(1)2(1) with Z' = 1, crystallized from ethanol), the molecules are linked into sheets of R(4)(4)(22) rings by a combination of one N-H.O hydrogen bond [H.O = 1.96 A, N.O = 2.833 (3) A and N-H.O = 171 degrees ] and one O-H.O hydrogen bond [H.O = 1.78 A, O.O = 2.614 (3) A and O-H.O = 173 degrees ]. In the monoclinic form (space group P2(1)/n with Z' = 2, crystallized from acetone), the molecules are linked by a combination of two N-H.O hydrogen bonds [H.O = 2.09 and 2.16 A, N.O = 2.873 (4) and 2.902 (3) A, and N-H.O = 147 and 141 degrees ] and two O-H.O hydrogen bonds [H.O = 1.84 and 1.83 A, O.O = 2.664 (3) and 2.666 (3) A, and O-H.O = 166 and 174 degrees ] into sheets of some complexity. These sheets are linked into a three-dimensional framework by a single C-H.O hydrogen bond [H.O = 2.45 A, C.O = 3.355 (4) A and C-H.O = 160 degrees ].