Alkynyldiphenylphosphine d8 (Pt, Rh, Ir) complexes: Contrasting behavior toward cis-[Pt(C6F5)2(THF) 2]

Article abstract of DOI:10.1021/ic048987j

The synthesis and characterization of a series of mononuclear d⁸ complexes with at least two P-coordinated alkynylphosphine ligands and their reactivity toward cis-[Pt(C₆F₅)₂(THF) ₂] are reported. The cationic [Pt(C₆F₅)- (PPh₂C=CPh)₃](CF₃SO₃), 1, [M(COD)(PPh₂C=CPh)₂](CIO₄) (M = Rh, 2, and Ir, 3), and neutral [Pt(o-C₆H₄E₂)-(PPh ₂C=CPh)₂] (E = O, 6, and S, 7) complexes have been prepared, and the crystal structures of 1, 2, and 7·CH ₃COCH₃ have been determined by X-ray crystallography. The course of the reactions of the mononuclear complexes 1-3, 6, and 7 with cis-[Pt(C₆F₅)₂(THF)₂] is strongly influenced by the metal and the ligands. Thus, treatment of 1 with 1 equiv of cis-[Pt(C₆F₅)₂(THF)₂] gives the double inserted cationic product [Pt(C₆F₅)(S)μ-{C-(Ph)= C(PPh₂)C(PPh₂)=C(Ph)(C₆F₅)}Pt(C ₆F₅)(PPh₂C=CPh)](CF₃SO₃) (S = THF, H₂O), 8 (S = H₂O, X-ray), which evolves in solution to the mononuclear complex [(C₆F5)(PPh₂C=CPh) Pt{C₁₀H₄-1-C₆F₅-4-Ph-2,3- κPP′(PPh₂)₂}](CF₃ SO₃), 9 (X-ray), containing a 1-pentafluorophenyl-2,3-bis(diphenylphosphine)-4- phenylnaphthalene ligand, formed by annulation of a phenyl group and loss of the Pt(C₆F₅) unit. However, analogous reactions using 2 or 3 as precursors afford mixtures of complexes, from which we have characterized by X-ray crystallography the alkynylphosphine oxide compound [(C₆F ₅)₂Pt(μ-κO:η²-PPh ₂(O)C=CPh)]₂, 10, in the reaction with the iridium complex (3). Complexes 6 and 7, which contain additional potential bridging donor atoms (O, S), react with cis-[Pt(C₆F₅)₂-(THF) ₂] in the appropriate molar ratio (1:1 or 1:2) to give homo- bi- or trinuclear [Pt(PPh₂C=CPh)(μ-κE-o-C₆H ₄E₂)-(μ-κP:η²-PPh ₂C=CPh)Pt(C₆F₅)₂] (E = O, 11, and S, 12) and [{Pt(μ₃-κ²EE′-o-C ₆H₄E₂)(μ-κP:η²-PPh ₂C≡ CPh)₂}{Pt(C₆F₅) ₂}₂] (E = O, 13, and S, 14) complexes. The molecular structure of 14 has been confirmed by X-ray diffraction, and the cyclic voltammetric behavior of precursor complexes 6 and 7 and polymetallic derivatives 11-14 has been examined.