Synthesis and Characterization of Heterobimetallic Complexes Derived from (o(Diphenylphosphino)benzoyl)pinacolone (HacacP). The Structure of PtCl2{Cu(acacP)2}

Debra A. Wrobleski, Cynthia S. Day, Bernard A. Goodman, Thomas B. Rauchfuss

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The synthesis and characterization of heterobimetallic complexes of (o-(diphenylphosphino)benzoyl)pinacolone are described. Reaction of 2 equiv of HacacP with MCl2(COD) (M = Pd, Pt), Rh2Cl2(CO)4, and IrCl(CO)2(p-H2NC6H4CH3) gave the metallo ligands of formulas ML2(HacacP)2 where ML2 = cis-PdCl2 and PtCl2 and trans-Rh(CO)Cl and Ir(CO)Cl. The ML2(HacacP)2 metallo ligands undergo smooth metalation by cupric carboxylates giving the heterobimetallic complexes of the formula ML2(Cu(acacP)2). The diamagnetic heterobimetallic complex PtCl2{Ti(acacP)2Cl2} was prepared from TiCl4 and PtCl2(HacacP)2. On the basis of 31P NMR, the Pt-Ti complex contains an unsymmetrical cis-TiCl2(acacP)2 subunit attached to a cis-PtCl2 moiety. Treatment of ZnEt2 with 2 equiv of HacacP followed by IrCl(CO)2(p-H2NC6H4CH3) gave trans-IrCl(CO){Zn(acacP)2}. The low-temperature 31P NMR spectrum of the Ir-Zn complex established the predominance of an isomer featuring trans but nonequivalent phosphines. By IR spectroscopy, the Ir-Zn and Ir-Cu complexes are structurally similar as are the Pd-Cu and Pt-Cu compounds. The Pt-Cu complex was characterized by single-crystal X-ray crystallography. PtCl2{Cu(acacP)2}·2CH2Cl 2·H2O crystallizes in the centrosymmetric triclinic space group P1-Ci1 (no. 2) with a = 11.914 (6) Å, b = 11.646 (6) Å, c = 21.125 (10) Å, α = 102.34 (4)°, β = 103.71 (4)°, γ = 99.83°, and Z = 2. The empirically weighted full-matrix least-squares refinement converged to R1 = 0.053 and R2 = 0.065 for 8881 independent reflections having 20 (Mo Kᾱ) < 55° and I > 3σ (I). The molecule consists of square-planar PtCl2P2 and Cu(β-diketonate)2 subunits with a nonbonding Pt⋯Cu separation of 3.97 A7ring;. Optical spectra of IrCl(CO){Cu(acacP)2} exhibit an intense absorption at 960 nm that is not found in typical square-planar Ir(I) or Cu(II) model compounds. This band disappears upon treatment with SO2, and the visible spectrum of IrCl(CO){Cu(acacP)2}·SO2 resembles that for a typical Cu(β-diketonate)2 chromophore. Similarly EPR studies indicate that the Pt-Cu and Ir-Cu-SO2 complexes consist of axially symmetric Cu moieties. EPR studies on IrCl(CO){Cu(acacP)2} indicate that it contains a low-symmetry Cu site (gx = 2.038, 2.146, 2.278) and a relatively small isotropic hyperfine splitting, both of which are consistent with the presence of a tetrahedrally distorted Cu(β-diketonate)2 unit. These data are consistent with the formation of an enolate bridge between iridium and copper centers.

Original languageEnglish (US)
Pages (from-to)5464-5472
Number of pages9
JournalJournal of the American Chemical Society
Issue number19
StatePublished - Sep 1 1984

ASJC Scopus subject areas

  • Catalysis
  • General Chemistry
  • Biochemistry
  • Colloid and Surface Chemistry


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