Competitive ligand/chelate binding in [Cu(TMPA)]+ and [Cu(tren)]+ based complexes

The competition between coordination of an incoming ligand (CO, CH3CN, PH3, H2O, MeOH, PhOH and O2 in its triplet state) and decoordination of one arm of the tripod is examined in the case of the [Cu(TMPA)]+ and [Cu(tren)]+ complexes from a theoretical point of view. It is shown that in the case of strong ligand (CO, CH3CN and PH3), arm and ligand coordination are competitive but that coordination of both is the most favored structure. In the case of ROH ligands, a structure with one arm decoordinated and interacting through H-bond with the hydroxyl hydrogen is found. This structure is of special interest as it allows liberation of one bonding site, which can be used for further dioxygen coordination. The consequences of these results on the oxidation of alcohols by dioxygen catalyzed by these classes of complexes are discussed.