Fulminic acid is an acid with the formula HCNO, more specifically H−C≡N⁺−O⁻. It is an isomer of isocyanic acid and of its elusive tautomer, cyanic acid, and also of isofulminic acid. Fulminate is the anion [C⁻≡N⁺−O⁻] or any of its salts. Wikipedia