What is a hypothetical compound, C2H2N4 which may be regarded as benzene with four CH groups replaced by nitrogen atoms; also, any of various derivatives of the same. There are three isomeric varieties called?

tetrazine — A hypothetical compound, C2H2N4 which may be regarded as benzene with four CH groups replaced by nitrogen atoms; also, any of various derivatives of the same. There are three isomeric varieties. (Webster's 1913.)

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