Polymorph VI of sulfapyridine: inter­penetrating two- and three-dimensional hydrogen-bonded nets formed from two tautomeric forms

Polymorph VI of 4-amino-N-(2-pyrid­yl)benzene­sulfonamide, C₁₁H₁₁N₃O₂S, is monoclinic (space group P2₁/n). The asymmetric unit contains two different tautomeric forms. The structure displays N—H...N and N—H...O hydrogen bonding. The two independent mol­ecules form two separate two- and three-dimensional hydrogen-bonded networks which inter­penetrate. The observed patterns of hydrogen bonding are analogous to those in polymorph I of sulfathia­zole.