Synthesis and structure of cis-PtX₂(P(t-Bu)₂CH₂CH₂CHCHCH₃) (X = Cl, Br), A platinum π-olefin complex formed by the intramolecular activation of a cyclopropylphosphine

The mixed chloro/bromo π-olefin complexes cis-PtX₂ (P(t-Bu)₂CH₂CH₂CHCHCH₃) )2) have been prepared by the reaction of Zeise's salt (K[PtCl₃(C₂H₄)]) with P(t-Bu)₂(CH₂CH₂CHCH₂CH₂) · HBr in boiling ethanol. The dimer complexes [PtX(P(t-Bu)₂CH₂CH₂CHCH₂CH₂)]₂ (μ-X)(μ-Y) (1) (X, Y Cl or Br) form first with subsequent activation of cyclopropane to give the monomeric π-olefin complexes (2). The mixed π-olefin complexes 2 co-crystallize. The average structure of 2 has been determined by X-ray methods. The relative occupanies in bromine for halogen sites cis- and trans- to coordinated olefin are 0.464(6) and 0.256(6), respectively. The olefin is symmetrically bound to the Pt atom (PtC 2.17(1) Å). The olefinic CC bond length is 1.38(1) Å.