2-Amino-4-nitrobenzothiazole

The crystal structure of the title compound, C₇H₅N₃O₂S, consists of centrosymmetric dimers, the principal intradimer interaction being two pairs of three-centre hydrogen bonds involving the amino group, the ring N atom and one O atom of the nitro group. The structure is compared with those of three unsubstituted 2-amino­benzothiazoles reported earlier. The molecule exists as a resonance hybrid of two tautomers, one neutral and the other dipolar. There is some indication that π density localized in the N_amino—C—N_ring portion of the molecule is in part transferred to the nitro group, but this should be confirmed by other techniques.

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