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

Abstract

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 oxygénation reaction, have been isolated and fully characterized including X-ray structural analyses. © WILEY-VCH Verlag GmbH,.