2-(Dicyanomethylene)croconate is a divalent anion with chemical formula C8N2O2−4 or ((N≡C−)2C=)(C5O4)2−. It is one of the pseudo-oxocarbon anions, as it can be described as a derivative of the croconate oxocarbon anion C5O2−5 through the replacement of one oxygen atom by a dicyanomethylene group =C(−C≡N)2. The anion was synthesized and characterized by A. Fatiadi in 1980, by hydrolysis of croconate violet treated with potassium hydroxide. It gives an orange solution in water.
See also Croconate violet, 1,3-bis(dicyanomethylene)croconate Croconate blue, 1,2,3-tris(dicyanomethylene)croconate 1,2-Bis(dicyanomethylene)squarate 1,3-Bis(dicyanomethylene)squarate
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