Metal-ligand bifunctional intermediate

Martin-Matute and coworkers described Cp Ir(III) complexes having hydroxyl-, ether-, and alkoxide-functionahzed NHC ligands, and their application in the N-alkylation of amines with primary and secondary alcohob [66]. In particular, the hydroxyl-functionalized complex dbplayed excellent catalytic outcomes, a broad substrate scope, and allowed amines to be alkylated with alcohob at temperatures as low as 50 °C. Indeed, thb hydroxyl-functionalized complex b one of the best catalysts known to date. The authors proposed a metal-ligand bifunctional mechanism for the iV-alkylation of amines with alcohob using this complex, which involves the formation of alcohol/alkoxide intermediates. Complex 38 (Figure 10.10) proved to be excellent for the A/,N -dialkylation of p-, m-, and 0-phenylenediamine with primary alcohob. The authors observed that the dimetal-lic compound 38 performs better than the monoiridium one, suggesting that a cooperative effect between the two metab may be at play [94]. 

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