necessary biochemical reactions in the plant this binding effect involves the oxime side chain and the enolic form of the 1 3 diketone to form a six member ring incorporating the metal ion the 5 position substitutions of three of the cyclohexanedione oximes clethodim sethoxydim and cycloxydim contains a chiral carbon atom as with many organic compounds these three cyclohexanedione oximes exist in optically active forms i e they have the ability to rotate the plane of plane polarized light in describing an optically active compound the prefixes d and 1 or s and r are used to denote the absolute configuration of the molecule about its chiral center s the prefixes d and 1 or and u2212 respectively are employed to designate the sign of rotation of plane polarized light by the compound with u2212 or 1 meaning that the compound is levorotatory a compound prefixed with or d is dextrorotatory for a given chemical structure these compounds called stereoisomers are identical except that they are mirror images of one another a specific stereoisomer may also be referred to as an enantiomer and a mixture of such enantiomers is often called an enantiomeric or racemic mixture enhanced activity of a single enantiomer over that of a racemic mixture and the other opposite enantiomer has not been taught or suggested based on studied modes of action of these compounds clethodim.