Nucleophiles hardness

In addition, a catalytic version of Tt-allylpalladium chemistry has been devel-oped[6,7]. Formation of the Tr-allylpalladium complexes by the oxidative addition of various allylic compounds to Pd(0) and subsequent reaction of the complex with soft carbon nucleophiles are the basis of catalytic allylation. After the reaction, Pd(0) is reformed, and undergoes oxidative addition to the allylic compounds again, making the reaction catalytic.-In addition to the soft carbon nucleophiles, hard carbon nucleophiles of organometallic compounds of main group metals are allylated with 7r-allylpalladium complexes. The reaction proceeds via transmetallation. These catalytic reactions are treated in this chapter. 

The thermodynamic tendency of a substance to act as a Lewis base. The strength of a Lewis base depends on the nature of the acid with which the Lewis base forms a Lewis adduct. Hence, comparative measures of Lewis basicities are given by equilibrium constants for the formation of the adducts by a common reference acid. See Lewis Base Nucleophilicity Hard Bases Soft Bases Donor Number... 

As for pyrones. the nature of the nucleophile (hard or soft) determines whether reactions occur at the carbonyl group or at the atom of the enone system. Electrophiles attack in I he benzene ring. 

Type of nucleophile soft nucleophiles hard nucleophiles... 

The regiochemistry of nucleophilic addition to an alkene or alkyne stabilized by a carbonyl group is a function of both the substrate and the nucleophile. Hard nucleophiles such as Grignard reagents tend to add... 

Pearson systematized metal ions into three categories according to their reactivity toward nucleophiles hard, intermediate, and soft. Hard metal ions, such as Fe(III),... 

The soft nucleophile-soft electrophile combination is normally associated with a late transition state where the strength of the newly forming bond contributes significantly to the stability of the transition state. The hard nucleophile-hard electrophile combination implies an early transition state with electrostatic attraction... 

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