Dinuclear platinum complexes olefins

Scheme 7 Olefin dioxy-functionalization with a dinuclear platinum complex...

Since it is known that the tetranuclear mixed-valent platinum blue and tan complexes such as 1 and 2 undergo disproportionation and reduction by water as Eqns. 1-3 and 7-9 show [54] [66], all the species appearing in Eqns. 1-3 and 7-9 are present in the solution. However, only one or several of the four species in the solution may in fact be active during catalytic olefin oxidation. To clarify this point, the effects of the Pt oxidation state in the platinum complexes were compared. The results are summarized in Table 2. It clearly shows that the dinuclear Pt111 complex is most effective, and is likely to be a true catalyst. Compound 1 also exhibits high activity, whereas the dinuclear Pt11 complex is ineffective. All other factors expected to affect the catalytic efficiency, including the presence of 02, the surfactant and the choice of solvent, have been examined and the results are summarized... 

Since tetranuclear platinum-blues are oxidized by 02 to Pt(III) dinuclear complexes and are reversively reduced to the platinum-blues and further to the Pt(II) dinuclear complexes, an attempt was made to use these complexes as catalysts for olefin oxidation to ketones and epoxides. The catalysts used were a-pyrrolidonato-bridged Pt-tan [Pt4(NH3)8(C4H6N0)4](N03)6 -2H20 (19), pivalamidato-bridged Pt-blue [Pt4(NH3)8(C5H10NO)4](NO3)5 (57), a-pyrrolidonato-tan [Pt4(NH3)8... 

Hydroxo-bridged dinuclear complexes, [Pt(P-P)(/u-OH)]2 (where P-P = DIOP, BINAP, NORPHOS, MeDUPHOS, and BPPM) as precursors have been used for the enantioselective Baeyer-Villiger oxidation of ketones (290). The platinum(O) catalyst precursor, Pt(MeDUPHOSXfrans-stylbene), catalyzes the asymmetric hydrophosphination of activated olefins (291). 

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