75560-03-1Relevant academic research and scientific papers
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.
supporting information, p. 2995 - 3002 (2021/09/13)
[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.
A new precatalyst for the Suzuki reaction - A pyridyl-bridged dinuclear palladium complex as a source of mono-ligated palladiuin(0)
Beeby, Andrew,Bettington, Sylvia,Fairlamb, Ian J. S.,Goeta, Andres E.,Kapdi, Anant R.,Niemelae, Elina H.,Thompson, Amber L.
, p. 600 - 605 (2007/10/03)
A dinuclear pyridyl-bridged palladium complex, trans-(P,N)-[PdBr(μ- C5H4N-C2,N)(PPh3)]2 1, was obtained from material isolated from the Suzuki cross-coupling reaction of 2-bromopyridine with 2,4-difluorophenylboronic acid in the presence of catalytic (PPh3)4Pd. Complex 1 is an effective precatalyst for the Suzuki cross-coupling reactions of a variety organoboronic acids and aryl bromides, and represents a useful source of mono-ligated palladium(0), "(Ph3P)Pd(0)".
Synthesis and electrospray mass spectrometry of palladium(II) diphosphine complexes from oxidative addition of 2-bromopyridine to Pd0
Chin, Clavius C. H.,Yeo, Jeremy S. L.,Loh,Vittal,Henderson,Hor, T. S. Andy
, p. 3777 - 3784 (2007/10/03)
Oxidative addition reactions of palladium(0) phosphine complexes with 2-bromopyridine gave rise to a series of structurally distinctive complexes, namely trans-(N,P)-[Pd2Br2(PPh3) 2(μ-C5H4N-C2,N)2] 1, [Pd2(μ-C5H4N-C2,N) 2-(μ-dppm)2]Br2 2, [Pd2(η1-dppp)2-(μ-C5H 4N-C2,N)2(μ-dppp)]Br2 3, trans-[{PdBr(η1-C5H4N-C 2)(μ-dppb)}n] 4, trans-(N,P)-[Pd2Br2(μ-C5H 4N-C2,N)2(μ-dppb)] 5 and cis-[PdBr(η1-C5H4NH-C 2)(η2-dppf)]Br 6 [Ph2P(CH2)nPPh2, n = 1(dppm), 3(dppp) or 4(dppb); dppf= Fe(Ph2PC5H4)2]. Similarly, trans-(N,P)-[Pd2Cl2(μ-C9H 6N-C2,N)2(μ-dppb)] 7 has been obtained from 2-chloroquinoline and [Pd(dppb)2]. An array of structural possibilities is envisaged based on the different co-ordination modes of the pyridine (C or/and N bonded; terminal or bridging; pyridyl, pyridine or pyridinium), phosphine (terminal, bridging or chelating) bromide (terminal or ionised) ligands. Complexes 2 and 3, but not the others, can be obtained from phosphine exchange reactions of 1. Complexes 5 and 6 were analysed by X-ray single-crystal crystallographic methods. The former reveals a dinuclear structure with a dppb ligand bridging diagonally two metals that are juxtaposed by two syn-bridging pyridyl groups. It represents an unusual dinuclear core stabilised by two types of bridging ligands of contrasting steric and geometric demands. The latter shows a cationic and mononuclear square planar palladium(II) complex containing a chelating dppf, terminal bromide and an unusual C-bonded pyridyl group with the N-site protonated. The fragmentation of these complexes was investigated by electrospray mass spectrometry under different cone voltages. Breakdown of the dinuclear framework is facilitated by addition of H-Br to the N-Pd bonds of the bridging pyridyl group.
Organopalladium(II) Complexes Containing Carbon-Bonded Heterocycles as a Ligand
Isobe, Kiyoshi,Nanjo, Kazuharu,Nakamura, Yukio,Kawaguchi, Shinichi
, p. 2141 - 2150 (2007/10/02)
Oxidative addition reactions of 2-chloropyridine, 2,6-dichloropyridine, 2-chloropyrazine, and 2-chlorobenzothiazole with tetrakis(triphenylphosphino)palladium(0) gave 2> or trans-depending on the nature of the carbon-bonded heterocycles R.They are all stable and the chloride ligand is readily replaced by other halides and pseudohalides.These novel organopalladium(II) complexes were characterized by the analytical and molecular-weight data together with IR, 1H NMR and 13C NMR spectra, and the 2-pyridyl-bridged dinuclear structure of 2)(PPh3)>2> was previously revealed by X-ray analysis.Both of the dinuclear and mononuclear 6-chloro-2-pyridylpalladium(II) complexes catalyze the cross coupling reaction between 2,6 dichloropyridine and methylmagnesium bromide to afford 2-methyl-6-chloropyridine selectively.The mononuclear 6-chloro-2-pyridylpalladium(II) complexes react with carbon monoxide to form the acyl complexes.
