Cu(i)-O₂ oxidation reactions in a fluorinated all-O-donor ligand environment

Investigation of Cu-O2 oxidation reactivity is important in biological and anthropogenic chemistry. Zeolites are one of the most promising Cu/O based oxidation catalysts for development of industrial-scale CH4 to CH3OH conversion. Their oxidation mechanisms are not well understood, however, highlighting the importance of the investigation of molecular Cu(i)-O2 reactivity with O-donor complexes. Herein, we give an overview of the synthesis, structural properties, and O2 reactivity of three different series of O-donor fluorinated Cu(i) alkoxides: K[Cu(OR)2], [(Ph3P)Cu(μ-OR)2Cu(PPh3)], and K[(R3P)Cu(pinF)], in which OR = fluorinated monodentate alkoxide ligands and pinF = perfluoropinacolate. This breadth allowed for the exploration of the influence of the denticity of the ligand, coordination number, the presence of phosphine, and KF/O interactions on their O2 reactivity. KF/O interactions were required to activate O2 in the monodentate-ligand-only family, whereas these connections did not affect O2 activation in the bidentate complexes, potentially due to the presence of phosphine. Both families formed trisanionic, trinuclear cores of the form {Cu3(μ3-O)2}3-. Intramolecular and intermolecular substrate oxidation were also explored and found to be influenced by the fluorinated ligand. Namely, {Cu3(μ3-O)2}3- from K[Cu(OR)2] could perform both monooxygenase reactivity and oxidase catalysis, whereas those from K[(R3P)Cu(pinF)] could only perform oxidase catalysis.