Amines as ligands

What are the similarities and differences in the behavior of a-acetamido-cinamic acid and allyl amine as ligands in asymmetric hydrogenation and isomerization reactions, respectively ... 

Bulky electron rich phosphino-amines as ligands for the Suzuki coupling reaction of aryl chlorides... 

BULKY ELECTRON RICH PHOSPHINO-AMINES AS LIGANDS FOR THE SUZUKI COUPLING REACTION OF ARYL CHLORIDES... 

In many cases the catalyst complex consists of a Cu(I) halide with multiden-tate aliphatic tertiary amines as ligands (eg A,A,A(, )V",Ar"-pentamethyl diethylene triamine, PMDETA). This ligand is cheap and provides relatively high rates of polymerization with still a reasonable degree of control. One of the peculiarities of this ligand is the fact that the Cu(II) complex has very limited solubility. In a study by Snijder and co-workers it is shown by ESR that a ceiling Cu(II) concentration is reached early in the polymerization of MMA. When this happens, the equations 1 and 2 no longer describe the monomer conversion versus time properly. On the basis of the experimental observation of constant deactivator concentration, Snijder derived a new expression that adequately describes monomer conversion versus time (55). 

To measure the relative rates of various ligands to replace CO, chemists must turn to competition experiments (see Section 8.8.3). Competition experiments using the coordi-nately unsaturated 16-electron species Ni(CO)a, Fe(CO)4, and Mo(CO)s, and alkenes, phosphines, and amines as ligands show only small differences in product ratios (between 1 and 10). Because these three 16-electron coordinately unsaturated species are not very selective in their reactions, they must all be very reactive. They react with almost any nucleophile with a very low energy of activation. In support of this view, the rate constants for the addition of the new ligands to such unsaturated systems have been estimated to be near 10 M s that is, they are approaching diffusion control. 

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