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Illustrative, non-limiting examples of the iodonium cation of formula ( d5) are given below. 

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Examples of the non-nucleophilic counter ion represented by M- include halide ions such as chloride and bromide ions; fluoroalkylsulfonate ions such as triflate, 1, 1, 1-trifluo› romethanesulfonate, and nonafluorobutanesulfonate; arylsulfonate ions such as tosylate, benzenesulfonate, 4-fluorobenzenesulfonate, and 1,2,3,4,5-pentafluorobenze› nesulfonate; alkylsulfonate ions such as mesylate and butanesulfonate; imide ions such as bis(trifluoromethyl› sulfonyl)imide, bis(perfluoroethylsulfonyl)imide and bis (perfluorobutylsulfonyl)imide; and methide ions such as tris( trifluoromethy lsulfonyl )methide and tris(perfluoroethy 1- sulfonyl )methide. 

Also included are a sulfonate ion which is fluorinated at a-position as represented by the formula (F-1) and a sulfonate ion which is fluorinated at a- and ~-positions as represented by the formula (F-2). 

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In formula (F-1), R 19 is hydrogen, or a C$_{1}$-C$_{20 }$ alkyl group, C$_{2}$-C$_{20 }$ alkenyl group or C$_{6}$-C$_{20 }$ aryl group, which may have an ether bond, ester bond, carbonyl moiety, lactone ring or fluorine atom. Herein the alkyl and alkenyl groups may be straight, branched or cyclic. 

In formula (F-2), R 20 is hydrogen, or a C$_{1}$-C$_{30 }$ alkyl group, C$_{2}$ -C$_{30 }$acyl group, C$_{2}$ -C$_{20 }$alkenyl group, CcC$_{20 }$ aryl group or C$_{1 }$-C$_{20 }$ aryloxy group, which may have an ether bond, ester bond, carbonyl moiety or lactone ring. Herein the alkyl, acyl and alkenyl groups may be straight, branched or cyclic. 

Examples of the recurring units (dl) are given below, but not limited thereto. Notably RA is as defined above. 

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Examples of the recurring units (d2) are given below, but not limited thereto. Notably RA is as defined above. 

