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

Abstract

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.

Catalytic Nitrene Transfer To Alkynes: A Novel and Versatile Route for the Synthesis of Sulfinamides and Isothiazoles

“…The most active catalysts were Cu(OTf) and Tp Br3 Cu(NCMe), in line with previous reports of being good catalysts for olefin aziridination reactions . Albeit both compounds displayed similar activities, we chose the complex Tp Br3 Cu(NCMe) to develop the scope of this system, in view of its remarkable stability in air, not only in the solid state but also in dichloromethane solution …”

A competing, dual mechanism for catalytic direct benzene hydroxylation from combined experimental-DFT studies

“…In a previous report from one of our laboratories we also found that a series of Tp x Cu complexes reacted with dioxygen and carbon dioxide in a consecutive sequence leading to dinuclear carbonato-bridged complexes. 24 Thus, we wondered about a possible implication of dinuclear intermediates in the aromatic hydroxylation reactions described in this contribution, in spite of being performed with hydrogen peroxide, and not with molecular oxygen. A series of catalytic experiments of benzene oxidation were run, varying the concentration of the catalyst [Tp *,Br Cu(NCMe)] from 0.0166 mM to 0.0666 mM.…”

The TpxM Core in Csp3–H Bond Functionalization Reactions: Comparing Carbene, Nitrene, and Oxo Insertion Processes (Tpx = Scorpionate Ligand; M = Cu, Ag)

“…On the other hand, the oxidation reaction of cyclohexane with H 2 O 2 was also reported with several Tp x Cu complexes (Scheme ), albeit in this case the overall reaction yield was maintained within the 10–22 % yield (cyclohexane‐based) despite the significant differences in electronic and steric properties of the Tp x ligand. Thus, Tp Br3 and Tp Me2 display similar steric hindrance around copper, but a large difference in the electronic effect onto the metal center (ca 51 cm –1 difference in the ν(CO) bands of their CO adducts) . Additionally, the bulkier Tp Ph does not show significant change in catalytic activity when compared with the parent Tp Me2 ‐containing catalyst.…”