Abstract Reactions of 3-nitro-1, 5-diarylformazans 1a-c with carbanions of acetylacetone, dibenzoylmethane, aceto-acetanilide, benzoylacetonitrile, ω-benzenesulfonylacetophenone and malononitrile yielded the corresponding 3-arylazopyrazole derivatives 4-9 respectively. Reactions of 1 with nucleophiles result in displacement of the nitro group and the formation of the corresponding 3-substituted formazans 10-13. Treatment of 1 with potassium ...