The present disclosure relates to a compound of the formula I or a tribologically acceptable salt, solvate, hydrate, or proadditive thereof, wherein R1, R2 and R4 are as defined herein. Such novel pyrrolidine, or succinimide, derivatives may be useful as friction modifiers in lubricant compositions. This disclosure also relates to a method of using such friction modifier compounds in lubricating fluid formulations to lubricate machine parts, including gear, axle, engine, and transmission parts, and to lubricant compositions containing such friction modifier compounds.