same pattern. Unified equation In an effort to unify the above described equations the Mayr equation is rewritten as: with sE the electrophile-dependent slope parameter and sN the nucleophile-dependent slope parameter. This equation can be rewritten in several ways: with sE = 1 for carbocations this equation is equal to the original Mayr–Patz equation of 1994, with sN = 0.6 for most n nucleophiles the equation becomes or the original Scott–Swain equation written as: with sE = 1 for carbocations and sN = 0.6 the equation becomes: or the original Ritchie equation written as: Types Examples of nucleophiles are anions such as Cl−, or a compound with a lone pair of electrons such as NH3 (ammonia) and PR3. In the example below, the oxygen of the hydroxide ion donates an electron pair to form a new chemical bond with the carbon at the end of the bromopropane molecule. The bond between the carbon and the bromine then undergoes heterolytic fission, with the bromine atom taking the donated electron and becoming the bromide ion (Br−), because a SN2 reaction occurs by backside attack. This means that the hydroxide ion attacks the carbon atom from the other side, exactly opposite the bromine ion. Because of this backside attack, SN2 reactions result in a inversion of the configuration of the electrophile. If the electrophile is chiral, it typically maintains its chirality, though the SN2 product's absolute configuration is flipped as compared to that of the original electrophile. An ambident nucleophile is one that can attack from two or more places, resulting in two or more products. For example, the thiocyanate ion (SCN−) may attack from either the sulfur or the nitrogen. For this reason, the SN2 reaction of an alkyl halide with SCN− often leads to a mixture of an alkyl thiocyanate (R-SCN) and an alkyl isothiocyanate (R-NCS). Similar considerations apply in the Kolbe nitrile synthesis. Halogens While the halogens are not nucleophilic in their diatomic form (e.g. I2 is not a nucleophile), their anions are good nucleophiles. In polar, protic solvents, F− is the weakest nucleophile, and I− the strongest; this order is reversed in polar, aprotic solvents. Carbon Carbon nucleophiles are often organometallic reagents such as those found in the Grignard reaction, Blaise reaction, Reformatsky reaction, and Barbier reaction or reactions involving organolithium reagents and acetylides. These reagents are often used to perform nucleophilic additions. Enols are also carbon nucleophiles. The