Effects of the Substituents in the Tp^xCu Activation of Dioxygen: An Experimental Study

A series of TpxCu(I) complexes (Tpx = homoscorpionate ligand) have been reacted in solution with dioxygen at room temperature. Two different behaviors have been observed: the already described reaction with O2 or the lack of any transformation. The trend has been correlated with the electronic density at the metal center, and that has been evaluated by means of cyclic voltammometry studies as well as by IR studies with the TpxCu(CO) complexes. The data collected indicate that the former could serve as a better tool to predict such transformation, establishing a limit above which the complexes are stable under oxygen in solution. Catalytic tests carried out under oxygen have demonstrated that the use of an inert atmosphere is not a requirement in some cases.