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((t)BA(F)Ph)(COD), Pt((t)BA(F)Ph)(nbd), and Pt(O(2)C(6)H(2)(t)u(2))(COD) (H(2)(t)BA(F)Ph = 2-(2-trifluoromethyl)anilino-4,6-di-tert-butylphenol, (H2O2C6H2Bu2)-Bu-t = 3,5-di-tert-butylcatechol) complexes were examined by cyclic voltammetry. Treatment of Pt((t)BA(F)Ph)(COD) or Pt((t)BA(F)Ph)(nbd) with AgPF6 afforded the imino-semiquinones [Pt((t)BA(F)Ph)(COD)]PF6 or [Pt((t)BAFPh)(nbd)]PF6, respectively. The [Pt((t)BAFPh)(COD)] complex was unreactive toward nucleophiles, whereas the oxidized derivative, [Pt((t)BAFPh)(COD)]PF6, rapidly and stereospecifically added alkoxides at the carbon trans to the phenolate. The Pt((t)BA(F)Ph)(COD), [Pt((t)BA(F)Ph)(COD)]PF6, Pt((t)BA(F)Ph)(C8H12OMe), and [Cp2Co][Pt((t)BA(F)Ph)(C8H12OMe)] complexes were characterized crystallographically.