Electron-transfer induced cleavage and formation of C-H-bonds in 17? and 19? platinum complexes

Abstract

The electrochemical behavior of platinum complexes [Pt(η4-diene)(η5-C5R5)]+BF4− (1+, diene = C5Me5H, R = H;2+, diene = C5Me5H, R = Me;3+, diene = C6H8, R = Me;4+, diene = C8H12, R = Me) was studied by cyclic voltammetry. Complexes1+ and2+ are shown to be capable of both oxidation and reduction. One-electron reduction of2+ gives a mixture of two neutral isomeric complexes5a,b of η3-allylic and σ,π,-olefinic type due to the cleavage of C-H bonds in the methyl groups of the pentamethylcyclopentadiene ligand of 19ē complexes2. The preparative electrochemical oxidation of2+ results in cleavage of the C-H bond at the sp3-hybridized pentamethylcyclopentadiene carbon atom in 17ē dication radical22+ to give the decamethylplatinocene dication [Pt(η5-C5Me5)2]2+(BF4)2 (72+). It is shown that one-electron reduction of72+ and one-electron oxidation of5a,b is accompanied by the formation of C-H bonds to form2+.