COBALT-CATALYZED SELECTIVE OXIDATION OF THE TRITERTIARY PHOSPHANE TRIPHOS WITH MOLECULAR-OXYGEN

The reactivity of complexes of triphos [CH3C(CH2PPh2)(3)] and CoCl2 to wards dioxygen has been investigated Reaction of the pseudo-tetrahedra l complex (eta(2)-triphos)CoCl2 (1) with dioxygen yields after work-up the mixed phosphane/phosphane oxide ligands triphosO and triphosO(2). The novel ligand triphosO(2) can be obtained in quantitative yield us ing catalytic amounts of 1. In order to gain some insight into the cat alytic dioxygen activation reaction, experiments with various triphos/ Co/Cl species, in different solvents and at several concentrations hav e been carried out. A mechanism involving two separate reaction pathwa ys is proposed. Complexes of triphosO and triphosO(2) with CoCl2, [eta (2)-(P,P)-triphosO]CoCl2 (4), and [eta(2)-(P, O)-triphosO(2)]CoCl2 (5) , which are present as intermediates in the oxygenation reaction, have been isolated and fully characterized including X-ray structural anal yses.