OBSERVATIONS ON OLEFIN OXIDATION BY NEUTRAL AND CATIONIC PHOSPHINEIRIDIUM COMPLEXES

Article abstract of DOI:10.1016/0022-328X(85)87022-4

The ethyleneiridium oxygen complex ClIr(PPh3)2(O2)(C2H4) previously prepared by Van der Ent, decomposes in solution forming some Ph3PO and CH3CHO, in the absence of excess ethylene.It promotes the oxidation of 1-octene and styrene by O2 and factors affecting the rate and efficiency of oxidation have been examined.Tetrastyrene di-μ-chlorodiiridium is only oxidised effectively by O2 in the presence of PPh3.The 1-octene complex ClIr(PPh3)2(C8H16) reacts very rapidly with oxygen at low temperatures but 2-octanone is not found in the decomposition products.The cationic complex (C2H4)Ir⁺(PPh3)2 promotes the oxidation of 1-octene and styrene but low yields of products are formed, including phenyloxirane and benzaldehyde.Complexes of 5-phenyldibenzophosphole were examined.They are not effective in promoting oxidation and display a strong tendency to form stable five-coordinate complexes and a greater propensity for cis-biphosphine coordination.