Cyclometalated platinum(II) complexes (C-P)Rt(Aryl)py undergo oxidative addition reaction upon treatment with electrophilic fluorination reagents, XeF2 or N-fluoro-2,4,6-trimethylpyridinium tetrafluoroborate, giving eventually products of C-C coupling. However, when aryl = mesityl, the two reagents give completely different products: the N-F salt still favors the C-C coupling reaction while XeF2 gives the unprecedented benzylic fluorination of one of the ortho-methyl groups of the mesityl ligand.