Preparation of some cyclopentadienyl platinum (IV) complexes

Two routes to the synthesis of (η⁵-C₅H₅)PtR₁R₂R3, where R₁, R₂, and R₃ are not all CH₃, were explored. The complexes [PtR₁R₂R₃X]₄, where R₁ = R₂ = CH₃, R₃ = C(O)CH₃, C₂H₅; R₁ = R₂ = C₂H₅, R₃ = CH₃, C(O)CH₃; R₁ = CH₃, R₂ = C₂H₅, R₃ = C(O)CH₃; X = Cl or I, were prepared and treated with TlCp to give (η⁵-C₅H₅)PtR₁R₂R₃. The latter are the first polyfunctionalized cyclopentadienyl platinum(IV) complexes. Conformational isomerism about the platinum to acetyl–carbon bond was detected by infrared spectroscopy. The cleavage of a Pt—CH₃ or Pt—C(O)CH₃ bond in CpPt(CH₃)₂R using the reagents HCl, HgCl₂, or I₂ was not successful; the appropriate [Pt(CH₃),RX]₄ being isolated instead. The chiral nature of (η⁵-C₅H₅)Pt(CH₃)(C₂H₅)[C(O)CH₃] is noted.