abstract |
Each of X1 and X2 is an alkyl group or the like that may have a substituent. Each of R11 to R18 is a hydrogen atom, an alkyl group that may have a substituent, or the like. Each of R21 and R22 is a hydrogen atom, an alkyl group that may have a substituent, or the like. A1− and A2− independently represent a monovalent anion, respectively. |