Carbene tagged ligands

Table 1.8 Structures of some carbene-tagged ligands.

Let us examine first the principal sites of tagging ruthenium complexes (Scheme 1.41) they include covalent ligands A [phosphines, N-heterocyclic carbenes (NHCs) or pyridine], anionic ligands B, or the carbene ligand C (either in the aromatic moiety or at the alkoxy ligand). 

In most tagging approaches to catalyst design the ionic group is installed on the carbene ligands, i.e. the benzylidene fragment. Table 1.8 collects a few examples. 

The NCH carbene ligand has also been exploited as tagging site. Two examples, 77 and 78, are quoted here, where the tag is a hydrophilic non-ionic PEG chain (Table 1.9). °... 

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