Cobalt-catalyzed selective oxidation of the tritertiary phosphane triphos with molecular oxygen

Article abstract of DOI:10.1002/cber.19971301007

The reactivity of complexes of triphos [CH₃C(CH₂PPh₂)₃] and CoCl₂ towards dioxygen has been investigated. Reaction of the pseudo-tetrahedral complex (η²-triphos)CoCl₂ (1) with dioxygen yields after work-up the mixed phosphane/phosphane oxide ligands triphosO and triphosO₂. The novel ligand triphosO₂ can be obtained in quantitative yield using catalytic amounts of 1. In order to gain some insight into the catalytic dioxygen activation reaction, experiments with va-nous triphos/Co/Cl species, in different solvents and at several concentrations have been carried out. A mechanism involving two separate reaction pathways is proposed. Complexes of triphosO and triphosO₂ with CoCl₂, [η²-(P,P)-in-phosO]CoCl₂ (4), and [η²-(P,O)-triphosO₂]CoCl₂ (5), which are present as intermediates in the oxygenation reaction, have been isolated and fully characterized including X-ray structural analyses. WILEY-VCH Verlag GmbH,.