The oxidative addition of PhCOCH2Cl to Pd(PPh3)4 led to a high yield of trans-[(PPh3)2(Cl)Pd(CH2COPh)], 3, in which the enolate is C-bonded to Pd(II), as shown by an X-ray analysis. Complex 3 reacts with ButNC., and depending on the stoichiometric ratio, two compounds were isolated. With a 1:1 stoichiometry, the insertion of ButNC into the PdC bond of 3 was observed and the crystalline solid 5 isolated, trans-[(PPh3)2(Cl)PdC-(NHBut)CHC(O) Ph], which contains the enolic form of a β-keto imino fragment. The reaction of 3 with 2 mol of ButNC led to a good yield (>70%) of an organic compound 7, which results from double insertion of ButNC on the PdC bond of 3, followed by homolytic cleavage of the PdC bond and dimerization of the resulting organic fragments. The ionization of the PdCl bond by AgCF3SO3 in acetonitrile led not to the cationic solvated form of 3, but rather to the dimer [{cis-(PPh3)2Pd}2(μ-CH2COPh)2]2+·2[CF3SO3]−, 9, containing the enolato anion bridging two palladium atoms in the oxoallyl form. In coordinating solvents, 9 is a source of the expected monomeric cationic form. Crystallographic details: 3 is monoclinic, space group Pn, a = 9.845(1) Å, b = 12.119(2) Å, c = 15.432(2) Å, α = γ = 90°, β = 95.29°, Z = 2, and R = 0.024; 5 is triclinic, space group P1̄, a = 12.040(1) Å, b = 18.473(2) Å, c = 11.922(1) Å, α = 97.25(1)°, β = 109.29(1)°, γ = 81.31°, Z = 8, and R = 0.072; 9 is monoclinic, space group I2/a, a = 21.550(2) Å, b = 34.773(3) Å, c = 22.592(2) Å, α = γ = 90°, β = 95.88(1)°, Z = 8, and R = 0.072.
Terminal and Bridging Bonding Modes of the Acetophenone Enolate to Palladium(II): The Structural Evidence and the Insertion of Isocyanides / P., Veya; C., Floriani; A., Chiesi Villa; Rizzoli, Corrado. - In: ORGANOMETALLICS. - ISSN 0276-7333. - 12:(1993), pp. 4899-4907. [10.1021/om00036a033]
Terminal and Bridging Bonding Modes of the Acetophenone Enolate to Palladium(II): The Structural Evidence and the Insertion of Isocyanides
RIZZOLI, Corrado
1993-01-01
Abstract
The oxidative addition of PhCOCH2Cl to Pd(PPh3)4 led to a high yield of trans-[(PPh3)2(Cl)Pd(CH2COPh)], 3, in which the enolate is C-bonded to Pd(II), as shown by an X-ray analysis. Complex 3 reacts with ButNC., and depending on the stoichiometric ratio, two compounds were isolated. With a 1:1 stoichiometry, the insertion of ButNC into the PdC bond of 3 was observed and the crystalline solid 5 isolated, trans-[(PPh3)2(Cl)PdC-(NHBut)CHC(O) Ph], which contains the enolic form of a β-keto imino fragment. The reaction of 3 with 2 mol of ButNC led to a good yield (>70%) of an organic compound 7, which results from double insertion of ButNC on the PdC bond of 3, followed by homolytic cleavage of the PdC bond and dimerization of the resulting organic fragments. The ionization of the PdCl bond by AgCF3SO3 in acetonitrile led not to the cationic solvated form of 3, but rather to the dimer [{cis-(PPh3)2Pd}2(μ-CH2COPh)2]2+·2[CF3SO3]−, 9, containing the enolato anion bridging two palladium atoms in the oxoallyl form. In coordinating solvents, 9 is a source of the expected monomeric cationic form. Crystallographic details: 3 is monoclinic, space group Pn, a = 9.845(1) Å, b = 12.119(2) Å, c = 15.432(2) Å, α = γ = 90°, β = 95.29°, Z = 2, and R = 0.024; 5 is triclinic, space group P1̄, a = 12.040(1) Å, b = 18.473(2) Å, c = 11.922(1) Å, α = 97.25(1)°, β = 109.29(1)°, γ = 81.31°, Z = 8, and R = 0.072; 9 is monoclinic, space group I2/a, a = 21.550(2) Å, b = 34.773(3) Å, c = 22.592(2) Å, α = γ = 90°, β = 95.88(1)°, Z = 8, and R = 0.072.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.