28516-49-6Relevant articles and documents
Reactivity of a Dinuclear PdIComplex [Pd2(μ-PPh2)(μ2-OAc)(PPh3)2] with PPh3: Implications for Cross-Coupling Catalysis Using the Ubiquitous Pd(OAc)2/nPPh3Catalyst System
Scott, Neil W. J.,Ford, Mark J.,Husbands, David R.,Whitwood, Adrian C.,Fairlamb, Ian J. S.
, p. 2995 - 3002 (2021)
[PdI2(μ-PPh2)(μ2-OAc)(PPh3)2] is the reduction product of PdII(OAc)2(PPh3)2, generated by reaction of ‘Pd(OAc)2’ with two equivalents of PPh3. Here, we report that the reaction of [PdI2(μ-PPh2)(μ2-OAc)(PPh3)2] with PPh3results in a nuanced disproportionation reaction, forming [Pd0(PPh3)3] and a phosphinito-bridged PdI-dinuclear complex, namely [PdI2(μ-PPh2){κ2-P,O-μ-P(O)Ph2}(κ-PPh3)2]. The latter complex is proposed to form by abstraction of an oxygen atom from an acetate ligand at Pd. A mechanism for the formal reduction of a putative PdIIdisproportionation species to the observed PdIcomplex is postulated. Upon reaction of the mixture of [Pd0(PPh)3] and [PdI2(μ-PPh2){κ2-P,O-μ-P(O)Ph2}(κ-PPh3)2] with 2-bromopyridine, the former Pd0complex undergoes a fast oxidative addition reaction, while the latter dinuclear PdIcomplex converts slowly to a tripalladium cluster, of the type [Pd3(μ-X)(μ-PPh2)2(PPh3)3]X, with an overall 4/3 oxidation stateperPd. Our findings reveal complexity associated with the precatalyst activation step for the ubiquitous ‘Pd(OAc)2’/nPPh3catalyst system, with implications for cross-coupling catalysis.
CRYSTAL STRUCTURE OF TRIS(TRIPHENYLPHOSPHINE) PALLADIUM
Sergienko, V. S.,Porai-Koshits, M. A.
, p. 548 - 552 (1987)
The authors have made an x-ray structural investigation of the reaction product of Pd2(PPh3)2*(μ-CO)(OAc)2 with a tertiary amine, identified in the course of x-ray structural analysis as Pd(PPh3)3.The crystals are triclinic: α=11.659, β=14.803, c=15.843 Angstroem, α=109.31, β=95.17, γ=90.49 deg, ρcalc=1.154 g/cm3, Z=2, space group PI.In the structure the coordination unit PdP3 has the form of a strongly distorted trigonal pyramid.The Pd atom is raised a little above the plane of P3 and is 0.160 Angstroem from it.The spacings of Pd-P are 2.307-2.322 Angstroem, and the values of the angles PPdP are 115.0-126.5 deg.The short intramolecular contacts Pd...H (2.82-2.03 Angstroem) to the ortho atoms of the Ph rings lie above and below the plane P3, blocking the axial positions at the Pd atoms.The results are compared with the literature data on complexes of zero-valent palladium with phosphine ligands.
Giant palladium clusters as catalysts of oxidative reactions of olefins and alcohols
Vargaftik,Zagorodnikov,Stolarov,Moiseev,Kochubey,Likholobov,Chuvilin,Zamaraev
, p. 315 - 348 (1989)
Giant cationic palladium clusters approximated as Pd561L60(OAc)180 (L = phen, bipy) and Pd561phen60O60(PF6)60 were synthesized and characterized with high resolution T
Photophysical Properties of Simple Palladium(0) Complexes Bearing Triphenylphosphine Derivatives
Kakizoe, Daichi,Nishikawa, Michihiro,Ohkubo, Takuma,Sanga, Masashi,Iwamura, Munetaka,Nozaki, Koichi,Tsubomura, Taro
, p. 9516 - 9528 (2021/06/28)
Pd(0) complexes with monodentate phosphine ligands, [Pd(P)n] (n = 3, 4), are well-known catalysts. However, the nature of the Pd(0) complex, especially the basic photophysical properties of the Pd(0) complexes, has not been extensively explored. In this work, we measured the general photophysical properties and crystal structures of Pd(0)-bearing PPh3 derivatives in the solid state and in solution. In the solid state, four-coordinated Pd(0) complexes exhibited blue-yellow emission. On the other hand, three-coordinated Pd(0) complexes displayed yellow-orange emission. In solution, orange emission of three-coordinated complexes was observed, and prompt fluorescence was detected using time-resolved emission spectroscopy, which suggests a thermally activated delayed fluorescence mechanism. Density functional theory (DFT) and time-dependent DFT calculations show that the difference in the transition mechanism between the [Pd(PPh3)4] and [Pd(PPh3)3] complexes explains the different emission colors. The emitting states of both complexes have metal-To-ligand charge-Transfer character, but the metal-centered d → p transition is considerably incorporated for emission of the tris complex.
On the Triple Role of Fluoride Ions in Palladium-Catalyzed Stille Reactions
Hervé, Marius,Lefèvre, Guillaume,Mitchell, Emily A.,Maes, Bert U. W.,Jutand, Anny
supporting information, p. 18401 - 18406 (2015/12/24)
The mechanism of Stille reactions (cross-coupling of ArX with Ar′SnnBu3) performed in the presence of fluoride ions is established. A triple role for fluoride ions is identified from kinetic data on the rate of the reactions of trans-[ArPdBr(PPh3)2] (Ar=Ph, p-(CN)C6H4) with Ar′SnBu3 (Ar′=2-thiophenyl) in the presence of fluoride ions. Fluoride ions promote the rate-determining transmetallation by formation of trans-[ArPdF(PPh3)2], which reacts with Ar′SnBu3 (Ar′=Ph, 2-thiophenyl) at room temperature, in contrast to trans-[ArPdBr(PPh3)2], which is unreactive. However, the concentration ratio [F-]/[Ar′SnBu3] must not be too high, because of the formation of unreactive anionic stannate [Ar′Sn(F)Bu3]-. This rationalises the two kinetically antagonistic roles exerted by the fluoride ions that are observed experimentally, and is found to be in agreement with the kinetic law. In addition, fluoride ions promote reductive elimination from trans-[ArPdAr′(PPh3)2] generated in the transmetallation step.
