Other Chelating Amido Ligands

Numerous other polyamido ligands that feature three or more nitrogen donor sites are known. In these, the nitrogens can be incorporated as part of a ring as they are in 1,4,7 triazacyclononanes (L), cyclams (M) or the tris(aminobenzyl)-1,4,7-triazacyclono-nane species (N).  

In addition, ligands of type O and related species have been used for the stabilization of middle and late high oxidation state transition metal complexes and the synthesis of oxidation catalysts 

Acyclic, multidentate amido ligands permit greater flexibihty in the coordination geometry of their complexes as exemplified by studies of diamidoamine and related ligands, a selection of which is illustrated by the structures P-U. 

The use of supporting amido ligands for transition metal based catalysts was intensified by reports of the use of bidentate amide donors of type V, with titanium and zirconium (the related ligand W is also known).  

In addition, chiral diamido ligands based on substituted 1,2-diaminocyclohexanes or diaminobinaphthalene have been prepared and tested for possible catalytic activity. 9.660 The use of amido ligands based on substituted 1,2-diaminobenzene and the reaction of 

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The design of polydentate ligands containing imines has exercised many minds over many years, and imine formation is probably one of the commonest reactions in the synthetic co-ordination chemist s arsenal. Once again, the chelate effect plays an important role in stabilising the co-ordinated products and the majority of imine ligands contain other donor atoms that are also co-ordinated to the metal centre. The above brief discussion of imine formation will have shown that the formation of the imine from amine and carbonyl may be an intra- or intermolecular process. In many cases, the detailed mechanism of the imine formation reaction is not fully understood. In particular, it is not always clear whether the nucleophile is metal-co-ordinated amine or amide. Some intramolecular imine formation reactions at cobalt(m) are known to proceed through amido intermediates. A particularly useful intermediate (5.24) in metal-directed amino acid chemistry is... 

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