15604-37-2Relevant academic research and scientific papers
Palladium-Catalyzed Formal Insertion of Carbenoids into Aminals via C-N Bond Activation
Qin, Guiping,Li, Lixin,Li, Jiawen,Huang, Hanmin
supporting information, p. 12490 - 12493 (2015/10/19)
A new strategy for selective insertion of metal carbenes into C-N bond has been developed via Pd-catalyzed C-N bond activation. A series of aminals and α-diazoesters with different substituents were successfully incorporated even in 0.1 mol % of catalyst under mild conditions, affording a wide range of α,β-diamino acid esters with quarternary carbon-centers. Preliminary mechanistic studies uncovered that the unique electrophilic cyclopalladated species could easily react with diazoacetates to generate a Pd-carbenoid intermediate which was involved in the catalytic cycle.
Donor-free phosphenium-metal(0)-halides with unsymmetrically bridging phosphenium ligands
Foerster, Daniela,Nickolaus, Jan,Nieger, Martin,Benko, Zoltan,Ehlers, Andreas W.,Gudat, Dietrich
, p. 7699 - 7708 (2013/07/26)
Reactions of (cod)MCl2 (cod = 1,5 cyclooctadiene, M = Pd, Pt) with N-heterocyclic secondary phosphines or diphosphines produced complexes [(NHP)MCl]2 (NHP = N-heterocyclic phosphenium). The Pd complex was also accessible from a chlorophosphine precursor and Pd2(dba) 3. Single-crystal X-ray diffraction studies established the presence of dinuclear complexes that contain μ-bridging NHP ligands in an unsymmetrical binding mode and display a surprising change in metal coordination geometry from distorted trigonal (M = Pd) to T-shaped (M = Pt). DFT calculations on model compounds reproduced these structural features for the Pt complex but predicted an unusual C2v-symmetric molecular structure with two different metal coordination environments for the Pd species. The deviation between this structure and the actual centrosymmetric geometry is accounted for by the prediction of a flat energy hypersurface, which permits large distortions in the orientation of the NHP ligands at very low energetic cost. The DFT results and spectroscopic studies suggest that the title compounds should be described as phosphenium-metal(0)-halides rather than conventional phosphido complexes of divalent metal cations and indicate that the NHP ligands receive net charge donation from the metals but retain a distinct cationic character. The unsymmetric NHP binding mode is associated with an unequal distribution of σ-donor/π-acceptor contributions in the two M-P bonds. Preliminary studies indicate that reactions of the Pd complex with phosphine donors provide a viable source of ligand-stabilized, zerovalent metal atoms and metal(0)-halide fragments.
Oxidative addition of Sn-C bonds on palladium(0): Identification of palladium-stannyl species and a facile synthetic route to diphosphinostannylene- palladium complexes
Cabon, Yves,Reboule, Irena,Lutz, Martin,Klein Gebbink, Robertus J. M.,Deelman, Berth-Jan
, p. 5904 - 5911 (2011/01/03)
Methyl-, phenyl-, and n-butyltin trichloride RSnCl3 (R = Me, Ph, nBu) react selectivily with palladium(0)-phosphine precursors through the unprecedented oxidative addition of the Sn-C bond. With [Pd(2-PyPPh2)3] (2-PyPPh2 = 2-pyridyldiphenylphoshine), the reaction cleanly leads to stable cationic dichlorostannylene palladium complexes of the general formula trans-[PdR(SnCl2(2-PyPPh2)2)][X] (X = Cl, R = Me ([5]Cl), R = Ph ([6]Cl), R = nBu ([11]Cl); X = RSnCl4, R = Me ([5][MeSnCl4]), R = Ph ([6][PhSnCl4]), R = nBu ([11][nBuSnCl4])). The SnCl 2(2-PyPPh2)2 fragment, formed by intramolecular coordination of the pyridyl groups to the dichlorostannylene moiety, can be considered as a self-assembled pincer-type ligand with a remarkable ability to suppress β-H elimination in its Pd-alkyl derivatives: [11][ nBuSnCl4], containing a Pd-nBu moiety, was found to be stable up to 70 °C. Oxidative addition of SnCl4 on [Pd(2-PyPPh2)3] resulted in trans-[PdCl(SnCl 2(2-PyPPh2)2)]Cl ([7]Cl) and trans-[PdCl(SnCl3(2-PyPPh2)2)] (8). The molecular structure of 8 was determined by single-crystal X-ray crystallography, indicating that the Sn atom of the trichlorostannyl function has an octahedral coordination geometry. In contrast, oxidative addition of the Sn-C bond of RSnCl3 on [Pd(PPh3)4] resulted in palladium trichlorostannyl complexes that were not stable toward cis-trans isomerization, (partial) elimination of SnCl2 (R = Me, Ph), or β-H elimination (R = nBu). The resulting mixtures of palladium alkyl and palladium hydride species were analyzed by multinuclear NMR, resulting in the identification of novel cis-[PdMe(SnCl3)(PPh3) 2] (cis-4), trans-[PdMe(SnCl3)(PPh3) 2] (trans-4), and cis-[PdH(SnCl3)(PPh3) 2] (cis-10) along with previously observed trans-[PdPh(Cl)(PPh 3)2] (1), trans-[PdMe(Cl)(PPh3)2] (3), trans-[PdH(SnCl3)(PPh3)2] (trans-10), and trans-[PdH(Cl)(PPh3)2] (9).
The electron-poor phosphines P{C6H3(CF 3)2-3,5}3 and P(C6F 5)3 do not mimic phosphites as ligands for hydroformylation. A comparison of the coordination chemistry of P{C 6H3(CF3)2-3,5}3 and P(C6F5)3
Clarke, Matthew L.,Ellis, Dianne,Mason, Kate L.,Orpen, A. Guy,Pringle, Paul G.,Wingad, Richard L.,Zaher, Damien A.,Baker, R. Tom
, p. 1294 - 1300 (2007/10/03)
The fluoroaryl phosphines P{C6H3(CF3) 2-3,5}3 (La) and P(C6F 5)3 (Lb) form the complexes trans-[MCl 2(La)2] and trans-[MCl2(L b)2] (M = Pd or Pt) which have been isolated and fully characterised. 31P NMR studies of competition experiments show that the stability of trans-[PdCl2L2] is in the order L = Lb a 3. The crystal structure of trans-[PtCl2(La)2] is reported and reveals that the Pt-P bond lengths in trans-[PtCl2L2] are in the order L = Lb a 3. The equilibria established when [Pt(norbornene)3] is treated with La or Lb are investigated by 31P and 195Pt NMR spectroscopy and the species [PtLn(norbornene)3-n] (n = 1-3) identified. Ligands La and Lb appear to have similar affinities for platinum(0). The complexes trans-[MCl(CO)(La) 2] and trans-[MCl(CO)(Lb)2] (M = Rh or Ir) have been synthesised and fully characterised; the values of vco are comparable with those for analogous phosphite complexes. The ligands L a, Lb, P(C6H2F 3-3,4,5)3 (Lc), P{C6H 4(CF3)-2}3 (Ld), PPh3 and P(OPh)3 have been tested in rhodium-catalysed hydroformylation of 1-hexene and La, Lb, and PPh3 have been tested in rhodium-catalysed hydroformylation of 4-methoxystyrene. Ligands L a, and Lb, have been shown to be stable under the hydroformylation catalysis conditions. For the 1-hexene reaction, the activity and selectivity for La and Lc are very similar to the PPh3 catalyst (TOF ca. 400 h-1; n: iso 2.5-3.0) but for the sterically demanding Lb and Ld the activity and selectivity was much lower than with PPh3 (TOF ca. 15, n: iso ratio 0.6). Thus, the yield of heptanals obtained with the catalyst derived from La is 94% while under the same conditions with Lb only 6%. The TOF for the La/Rh catalyst was 5 times lower than for the P(OPh)3/Rh catalyst despite the superficially similar ligand electronic characteristics for La and P(OPh)3. The Royal Society of Chemistry 2005.
Triphenyl-phosphine and -arsine analogues which facilitate the electrospray mass spectrometric analysis of neutral metal complexes
Decker, Corry,Henderson, William,Nicholson, Brian K.
, p. 3507 - 3513 (2007/10/03)
The six triarylphosphines PPhn(C6H4OMe-p)3-n and PPhn(C6H4NMe2-p)3-n (n = 0-3) and the arsine As(C6H4OMe-p)3 (L) have been synthesized and examined for their use in the electrospray mass spectrometric (ESMS) study of metal complexes. This has been tested with selected examples of the complexes [Mo(CO)4L2], [Fe(CO)3L2], [Fe(CO)4L], [Ru3(CO)9L3], cis-[PtCl2L2], [PdCl2L2] and [AuCl(L)]. All of the metal carbonyl complexes of these ligands gave [M + H]+ ions in their spectra, while in contrast the analogous PPh3 complexes do not, suggesting that these electrospray-friendly ligands should be useful for the characterisation of a wide range of complexes by ESMS. The incorporation of the ligands into metal halide complexes however does not allow the observation of [M + H]+ ions, with ions formed by the previously reported halide-loss mechanism being the only ones observed. The Royal Society of Chemistry 1999.
Reactions of Olefin Complexes with Nitrene Precursors. Synthesis of Triazoline and Aziridin Complexes of Palladium(II); Crystal and Molecular Structure of trans-Dichlorobis(11-phenyl-9,10,11-triazabicycloundec-9-ene-N9)palladium-Chloroform(1/2)
Porta, Francesca,Pizzotti, Maddalena,Monica, Gerolamo La,Finessi, Luis A.,Cenini, Sergio,et al.
, p. 2409 - 2414 (2007/10/02)
By reaction at 70 deg C of phenyl azide with a suspension of PdCl2 and cis-cyclo-octene, the complex has been isolated, and its crystal and molecular structure determined.This compound crystallizes in triclinic space group with a=9.258(2), b=10.702(3), c=11.156(2) Angstroem, α=113.94(3), β=99.60(2), γ=104.87(3) deg, and Z=1.The metal lies on a symmetry centre and the complex configuration is trans planar.The chloroform molecules are hydrogen bonded to the co-ordinated chloride ions.The reaction of phenyl azide with cis-cyclo-octene at 70 deg C in the absence of PdCl2 leads to the corresponding anil, N-cyclo-octylideneaniline, .Preformed 2> reacts with phenyl azide in cyclo-octene at 70 deg C to give .By comparison, has been synthesized from the reaction of with N-cyclo-octylideneaniline.
