Redox Activation of Alkene Ligands in Platinum Complexes with Non-innocent Ligands

The reactivity of metal olefin complexes with non-innocent ligands (NILs) was examined. Treatment of PtCl2(diene) with the deprotonated catechol or aminophenol ligands afforded the corresponding Pt(NIL)(diene) complexes. The Pt(tBAFPh)(COD), Pt(tBAFPh)(nbd), and Pt(O2C6H2tBu2)(COD) (H2tBAFPh = 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, H2O2C6H2tBu2 = 3,5-di-tert-butylcatechol) complexes were examined by cyclic voltammetry. Treatment of Pt(tBAFPh)(COD) or Pt(tBAFPh)(nbd) with AgPF6 afforded the imino-semiquinones [Pt(tBAFPh)(COD)]PF6 or [Pt(tBAFPh)(nbd)]PF6, respectively. The [Pt(tBAFPh)(COD)] complex was unreactive toward nucleophiles, whereas the oxidized derivative, [Pt(tBAFPh)(COD)]PF6, rapidly and stereospecifically added alkoxides at the carbon trans to the phenolate. The Pt(tBAFPh)(COD), [Pt(tBAFPh)(COD)]PF6, Pt(tBAFPh)(C8H12OMe), and [Cp2Co][Pt(tBAFPh)(C8H12OMe)] complexes were characterized crystallographically.