Also, when X1 and X2 in formula (I) represents an alkyl group, an aryl group, or a heterocyclic group each having a substituent and the nitrogen-containing heterocyclic group formed by the organic residue shown by X3 and >N-- in formula (II) has a substituent, examples of the substituent are a halogen atom (e.g., fluorine and chlorine), an alkoxycarbonyl group (having from 2 to 30, and preferably