ELECTRON-TRANSFER-INDUCED CLEAVAGE AND FORMATION OF C-H-BONDS IN 17(E)OVER-BAR AND 19(E)OVER-BAR PLATINUM COMPLEXES

The electrochemical behavior of platinum complexes [Pt(eta(4)-diene)(e ta(5)-C(5)R(5))](BF4-)-B-+ (1(+), diene = C(5)Me(5)H, R = H; 2(+), die ne = C(5)Me(5)H, R = Me; 3(+), diene = C6H8, R = Me; 4(+), diene = C8H 12, R = Me) was studied by cyclic voltammetry. Complexes 1(+) and 2(+) are shown to be capable of both oxidation and reduction. One-electron reduction of 2f gives a mixture of two neutral isomeric complexes 5a, b of eta(3)-allylic and sigma,pi-olefinic type due to the cleavage of C-H bonds in the methyl groups of the pentamethylcyclopentadiene ligan d of 19 $$($) over bar e complexes 2. The preparative electrochemical oxidation of 2(+) results in cleavage of the C-H bond at the sp(3)-hy bridized pentamethylcyclopentadiene carbon atom in 17 $$($) over bar e dication radical 2(2+) to give the decamethylplatinocene dication [Pt (eta(5)-C(5)Me(5))(2)](2+)(BF4)(2) (7(2+)). It is shown that one-elect ron reduction of 7(2+) and one-electron oxidation of 5a,b is accompani ed by the formation of C-H bonds to form 2(+).