One-Electron Oxidation of [M(PtBu3)2] (M= Pd, Pt): Isolation of Monomeric [Pd(PtBu3)2]+ and Redox-Promoted C-H Bond Cyclometalation

Abstract : Oxidation of zero-valent phosphine complexes [M(P t Bu 3) 2 ](M = Pd, Pt) has been investigated in 1,2-difluorobenzene solution using cyclic voltammetry and subsequently using the ferrocenium cation as ac hemical redox agent. In the case of palladium, am ononuclear paramagnetic Pd I derivative was readily isolated from solution and fully characterized (EPR, X-ray crystallography). While in situ electrochemical measurements are consistent with initial one-electron oxidation, the heavier congener undergoes CÀHbond cyclometalation and ultimately affords the 14 valence-electron Pt II complex [Pt(k 2 PC-P t Bu 2 CMe 2 CH 2)(P t Bu 3)] + with con-comitant formation of [Pt(P t Bu 3) 2 H] +.