Cyclometalated platinum(II) compounds with fluorinated iminic ligands: Synthesis and reactivity tuning. Crystal structures of the compounds [PtMe(RCH=NCH2C6H5)(PPh3)] (R = 2,3,4-C6HF3 and 2,3-C6H2F2)

Article abstract of DOI:10.1021/om00001a051

[Pt₂Me₄(μ-SMe₂)₂] (1) reacts with fluorinated imines ArCH=NCH₂C₆H₅ (2; Ar = 2,3,4-C₆H₂F₃, 2,4,5-C₆H₂F₃, 2,3-C₆H₃F₂) to yield the C,N-cyclometalated platinum(II) compounds [PtMe(RCH=NCH₂C₆H₅)(SMe₂)] (3) by ortho metalation with loss of methane. Complexes 3 react with triphenylphosphine to give cyclometalated compounds [PtMe(RCH=N-CH₂C₆H₅)(PPh₃)] (4). For R = 2,4,5-C₆HF₃, an excess of PPh₃ produces metallacycle cleavage, and [PtMe(RCH=NCH₂C₆H₅)(PPh₃) ₂] (5) is formed with the imine acting as a [C^-] unidentate ligand. Similarly, reactions of the previously reported compounds [PtMe{RCH=NCH₂(2-C₆H₄Cl)}(SMe₂)] (R = 3,5-C₆H₂F₂, 2-C₆H₃F, 5-C₆H₃F) with PPh₃ produce the cyclometalated compounds 4. When an excess of PPh₃ is used, compounds 5 are obtained only if there is a fluorine atom adjacent to platinum (F⁵). 3-5 were characterized by elemental analyses and NMR spectroscopy, and [PtMe(2,3,4-C₆HF₃CH=NCH₂C₆H ₅)(PPh₃)] (4a) and [PtMe(2,3-C₆H₂F₂CH=NCH₂C ₆H₅)(PPh₃)] (4c) were characterized crystallographically. 4a crystallizes in the monoclinic space group P2₁/c, with a = 12.475(3) A?, b = 21.642(5) A?, c = 10.497(2) A?, β = 96.92(2)°, and Z = 4. 4c crystallizes in the triclinic space group P1, with a = 12.031(2) A?, b = 13.757(2) A?, c = 9.768(2) A?, α = 72.91(2)°, β = 114.91(1)°, γ = 104.20(2)°, and Z = 2. Structural and NMR parameters for compounds 4 are discussed in relation to the observed reactivity of these compounds.