Croconate violet

Croconate violet or 1,3-bis(dicyanomethylene)croconate is a divalent anion with chemical formula C11N4O2−3 or ((N≡C−)2C=)2(C5O3)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 two oxygen atoms by dicyanomethylene groups =C(−C≡N)2. Its systematic name is 3,5-bis(dicyanomethylene)-1,2,4-trionate. The term croconate violet as a dye name specifically refers to the dipotassium salt K2C11N4O3.

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