Amide type ligands

Rare Earth Complexes with Amide Type Ligands... 

Figure 4.1 Six representative aliphatic amide type ligands.

The silyl amide type ligands have been used extensively in rare earth chemistry, as well as in actinide and transition metal chemistry, to stabilize electronically unsaturated metal centers due to the available lone pair on the nitrogen donor atom. Because of the relatively larger steric encumbrance, the rare earth complexes with silyl amide type ligands often exhibit low coordination numbers. As a consequence, the large and electropositive rare earth metal centers are accessible to external reagents, which make them more active in many reactions. 

Figure 4.6 Two representative silyl amide type ligands.

Some rigid tripodal ligands have been synthesized for the construction of various novel cage- or box-like complexes, and have demonstrated their potential use in supramolecular chemistry. The relatively flexible amide-type ligand (136) was prepared by the replacement reaction of 1,1,1-tris(p-tosyloxymethyl)propane and /V-benzylsalicylamide.217... 

Figure 3.3 TANIAPHOS and JOSIPFIOS-type ligands used in the asymmetric reduction of en amides...

The acceptor and donor strength of many functions besides fhose of fhe amide type have been characterized by the analysis of associations between simple molecules, such as, e.g., phenols and anilines, for which fhousands of experimental data exist, mosfly measured in chloroform or in carbon tetrachloride [94, 95]. Although these data are hampered by less well-defined structures compared to supramolecular complexes, they not only give a fairly consistent basis for the prediction of hydrogen-bonded associations but also can be used, e.g., for crown efher and cryptand complexes with alkali or ammonium ligands [32]. 

---