Three anilides of 2,2′-thio­di­benzoic acid

The structures of N,N′-bis­(2-methyl­phenyl)-2,2′-thio­dibenz­amide, C₂₈H₂₄N₂O₂S, (Ia), N,N′-bis­(2-ethyl­phenyl)-2,2′-thio­dibenzamide, C₃₀H₂₈N₂O₂S, (Ib), and N,N′-bis­(2-bromo­phenyl)-2,2′-thio­dibenzamide, C₂₆H₁₈Br₂N₂O₂S, (Ic), are com­pared with each other. For the 19 atoms of the consistent thiodibenzamide core, the r.m.s. deviations of the mol­ecules in pairs are 0.29, 0.90 and 0.80 Å for (Ia)/(Ib), (Ia)/(Ic) and (Ib)/(Ic), respectively. The conformations of the central parts of mol­ecules (Ia) and (Ib) are similar due to an intra­molecular N—H...O hydrogen-bonding inter­action. The mol­ecules of (Ia) are further linked into infinite chains along the c axis by inter­molecular N—H...O inter­actions, whereas the mol­ecules of (Ib) are linked into chains along b by an inter­molecular N—H...π contact. The conformation of (Ic) is quite different from those of (Ia) and (Ib), since there is no intra­molecular N—H...O hydrogen bond, but instead there is a possible intra­molecular N—H...Br hydrogen bond. The mol­ecules are linked into chains along c by inter­molecular N—H...O hydrogen bonds.