Amido ligands, hydroamination with

The proposed reaction mechanism involves intermolecular nucleophilic addition of the amido ligand to the olefin to produce a zwitterionic intermediate, followed by proton transfer to form a new copper amido complex. Reaction with additional amine (presnmably via coordination to Cn) yields the hydroamination prodnct and regenerates the original copper catalyst (Scheme 2.15). In addition to the NHC complexes 94 and 95, copper amido complexes with the chelating diphosphine l,2-bis-(di-tert-bntylphosphino)-ethane also catalyse the reaction [81, 82]. 

Abstract This review deals with the synthesis and the catalytic application of noncyclopentadienyl complexes of the rare-earth elements. The main topics of the review are amido metal complexes with chelating bidentate ligands, which show the most similarities to cyclopentadienyl ligands. Benzamidinates and guanidinates will be reviewed in a separate contribution within this book. Beside the synthesis of the complexes, the broad potential of these compounds in homogeneous catalysis is demonstrated. Most of the reviewed catalytic transformations are either C-C multiple bond transformation such as the hydroamination and hydrosilylation or polymerization reaction of polar and nonpolar monomers. In this area, butadiene and isoprene, ethylene, as well as lactides and lactones were mostly used as monomers. 

To understand the function of the ionic ate complexes in the catalytic hydroamination reactions, the neutral yttrium chloro complex 212 containing diamide ligand L44 was prepared by the reaction of YCI3 with 1 equiv of Li2L44 to compare with the ate complexes. The neutral yttrium amido complex 213 was obtained from reacting 212 with LiNlPr2 in THF (Scheme 78). 

Amidate and amidinate complexes of early metals are also known. In these complexes, the TT-bonding interaction is reduced because of the adjacent ir-system. These ligands may bind in a k - or K -fashion, or they can bind in an ir)Mashion with the metal interacting with the entire ir-system of the amidate, as shown in Figure 4.3. The synthetic routes used to prepare these complexes are similar to those used to prepare early-metal-amido complexes. The reactivity of these ligands is limited—most often they serve as ancillary ligands that modulate the steric and electronic properties of the central metal. As such, amidate complexes have been employed as catalysts for the hydroamination of terminal alkenes - and alkynes that is described in Chapter 14. 

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