Trifluoromethylsulfonyl
Triflyl, more formally known as trifluoromethanesulfonyl, is a functional group with the formula F3CSO2–. The triflyl group is often represented by –Tf.
The closely related triflate group (trifluoromethanesulfonate) has the formula F3CSO2O–, and is represented by –OTf.