- (Dihalogenmethyl)palladium(II)-Komplexe aus Palladium(0)-Vorstufen des Dibenzylidenacetons: Synthese, Strukturchemie and Reaktivitaet
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Bis(dibenzylideneacetone)palladium(0) (1) reacts with one equivalent of a chelating phosphine ligand (P-P) or two equivalents of a monophosphine ligand (P) to give complexes of the type (P-P)Pd(dba) (3a-c; dba=dibenzylidene acetone) and (P)2Pd(dba) (3d,e) respectively, that have been characterized spectroscopically and structurally (X-ray structure analysis).These complexes readily cleave the carbon-halogen bond of chloroform or bromoform.The air- and moisture-stable oxidative addition products (P-P)Pd(CHX2)X (4a-d; X=Cl, Br) are thus obtained in 70-85percent yield.Their identity was established by a single-crystal X-ray diffraction study of 4a.
- Herrmann, Wolfgang A.,Thiel, Werner R.,Brossmer, Christoph,Oefele, Karl,Priermeier, Thomas,Scherer, Wolfgang
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- Transformation of 1,3-imidazolidine-2-thione (SC3H6N2) into (SC3H4N2–O–N2C3H4S)2? dianion chelated in [Pd{κ 3–S, O, S–(SC3H
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Reaction of [PdCl2(PPh3)2] with imidazolidine-2-thione {SC3H4(NH)2}in the presence of triethylamine involved activation of N–H bonds and formed an unusual oxo-bridged dianion, (SC3/su
- Mehra, Vinny,Bains, Amreen Kaur,Hundal, Geeta,Lobana, Tarlok S
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- Cyclopalladation of 1-Tetralone (3,4-Dihydronaphthalen-1-one) Oximes
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Cyclopalladated complexes precipitate from methanolic Li2-Na solutions containing 1-tetralone oxime, the 6-methoxy-analogue, and the 7-substituted derivatives, substituent R = CH3-, Ch3CH2-, MeO-, but reaction fails when R = (CH3)2CH-, (CH3)3C-, or -NO2.The oxime derivatives of methyl 12-methoxy-7-oxopodocarpa-8,11,13-trien-19-oate and methyl 7-oxopodocarpa-8,11,13-trien-19-oate readily metallate while the oxime of methyl 7-oxoabieta-8,11,13-trien-18-oate does not.Carbonylation of the cyclopalladated 1-tetralone oxime complexes in methanol gives the corresponding 8-methoxycarbonyl-1-tetralone oximes. (1)H NMR analysis of 1-tetralone oxime and Li2 solutions show is not a reaction intermediate.At -76 deg C co-ordinated oxime exhibits a downfield shift for H8, characteristic of above-plane geometry of the ligand, while at 0 deg C an upfield shift relative to the free oxime suggests in-plane geometry.The intermediate isolable in water giving cis-*3H2O which on redissolving gives the soluble cyclometallated species (S = solvent) and HCl by an irreversible process.Dimerisation gives 2> or the complex in the presence of L (L = oxime or PPh3).
- Nielson, Alastair J.
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- Trinuclear Cu(I)–NHC as NHC transfer agent: Synthesis of mono- and di-nuclear palladium and mercury complexes
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Mono and dinuclear palladium–NHC complexes of 1,3-bis(2-pyridyl)imidazolin-2-ylidene (py2im) ligand, such as [Pd(py2im)2](PF6)2 (2) [Pd2Cl2(py2im)2](PF
- Santra, Biswajit
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- Preparation and Properties of the ?-Picolyl Complexes of Palladium(II), (n=0,1, and 2)
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The oxidative addition of 2-(chloromethyl)pyridine to tetrakis(triphenylphosphine)palladium (0) in toluene at 100 deg C gave (1a), which was charachterized by analitical, molecular-weight, and IR data as well as 1H, 31P, and 13C
- Isobe, Kiyoshi,Nakamura, Yukio,Kawaguchi, Shinichi
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- Light-induced Reactions of trans-Chloro(cyanomethyl)bis(triphenylphophine)palladium(II) and the Crystal and Molecular Structures of its Acetone, Acetonitrile, and Benzene Solvates
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x-Ray structuredeterminations have been completed for the acetone, acetonitrile, and benzene solvates of (PdCl(CH2CN)(PPh3)) (2).Crystals of (2)*acetone and (2)*acetonitrile are isomorphous, monoclinic, space group P21/n with four formula units in the unit cell.The acetone solvate has cel data: a = 12.679(4), b = 14.553(1), c = 19.506(5) Angstroem, and β = 94.72(1) deg; for tha acetonitrile solvate a = 12.581(2), b = 14.323(2), c = 19.359(3) Angstroem, and β = 93.85(1).The (2)*benzene crystals are also monoclinic, space group P21/a, with four formula units ina unit cell of dimensions a = 22.140(3), b = 10.058(1), c = 18.699(6) Angstroem, and β = 114.78(2) deg.The stuctures were solved by the heavy-atom method and refined by full-matrix least squares calculations to R = 0.026, 0.028, and 0.050 for 4907, 2998, 3664 observed reflections for the acetone, acetonitrile, and benzene solvates, respectivly.In all three complexes molecule (2) has slightly distorted square planar co-ordination with Pd-P 2.319-2.342(1), Pd-Cl 2.369(2)-2.394(1), and Pd-C 2.063(2)-2.088(6) Angstroem.In (2)*acetone and (2)*acetonitrile the solvent molecules are trapped in polar pockets whereas in (2)*benzene the benzenes of solvation are in non-polar channels.The structures show little evidence of an interactionof the nitrile carbon atom with the metal atom nor any obvious structural features that might explain the photochromic behaviour of crystalline (2).Irradiation of (2) with u.v. or tungsten lamps, either in the solid state or in solution, leads to similar products.In the presence of oxygene, in benzene, the principal products are trans-(PdCl2(PPh3)2) (3), ((PdCl(CH2CN)(PPh3))n) (4), ((PdCl2(PPh3))2) (5), PPh3O (6), and acetonitrile.The accumulation of (4) and (5) results from a loss of PPh3 (from (2) and (3) respectivly), the oxidation of which is probably catalysed b ya reduced palladium species generated by photolysis of (2).In the absence of oxygene, in benzene, the only products identified were (3) and acetonitrile whilst in chloroform essentially quantitative conversion of (2) into (3), acetonitrile, and some succinonitrile is observed.Although an e.s.r. investigation showed that radicals are generated uppon irradiation of (2) the principal mode of formation of acetonitrile appears to involve proton abstraction from traces of water in the solvent.The red colour assumed by cristallone (2) upon irradiation is lilmited to the surface.Similar colours have been obtained by heating or irradiating (2) in solution and by treating ethanolic solution of (3) with base.It is suggested that reduced palladium species are responsible for these colours.
- McCrindle, Robert,Ferguson, George,McAlees, Alan J.,Parvez, Masood,Roberts, Paul J.
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- Tertiary arsine ligands for the Stille coupling reaction
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The Stille coupling reaction is one of the most important coupling reactions. It is well known that the triphenylarsine ligand can accelerate the reaction rate of Stille coupling. However, other arsine ligands have never been investigated for the Stille c
- Chishiro, Akane,Imoto, Hiroaki,Inaba, Ryoto,Konishi, Masafumi,Naka, Kensuke,Yumura, Takashi
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- Synthesizing method of indanone compound
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The invention discloses a synthesizing method of an indanone compound. The synthesizing method comprises the following steps of respectively adding a catalyst and an antioxidant into a reaction bottle, then adding a compound shown in a formula (2), adding a solvent, and reacting for 2 to 6h at the temperature of 70 to 120 DEG C under the argon protection atmosphere, so as to obtain the indanone compound, wherein the catalyst is selected from any one of Cu(OAc)2, CuCl2 (copper (II) chloride), CuBr2 (copper (II) bromide), CuO (copper oxide), CuF2 (copper fluoride), Cu(OTf) 2, Cu(OH)2 (copper hydroxide), Cu(NO3)2 (copper nitrate), CuCl (copper chloride), CuBr (copper bromide), CuI (cuprous iodide) and Cu2O (cuprous oxide); the oxidant is tert-butyl hydroperoxide; the solvent is toluene. The synthesizing method has the advantages that a novel concept of the indanone compound is provided; the copper catalyst is used, the price of copper is low, the reserve amount is rich, the environment-friendly effect is realized, and the hydroacylation reaction catalyzed by copper meets the requirements of green chemistry.
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Paragraph 0087-0089
(2018/11/04)
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- Structural, Kinetic, and Computational Characterization of the Elusive Arylpalladium(II)boronate Complexes in the Suzuki-Miyaura Reaction
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The existence of the oft-invoked intermediates containing the crucial Pd-O-B subunit, the “missing link”, has been established in the Suzuki-Miyaura cross-coupling reaction. The use of low-temperature, rapid injection NMR spectroscopy (RI-NMR), kinetic studies, and computational analysis has enabled the generation, observation, and characterization of these highly elusive species. The ability to confirm the intermediacy of Pd-O-B-containing species provided the opportunity to clarify mechanistic aspects of the transfer of the organic moiety from boron to palladium in the key transmetalation step. Specifically, these studies establish the identity of two different intermediates containing Pd-O-B linkages, a tri-coordinate (6-B-3) boronic acid complex and a tetra-coordinate (8-B-4) boronate complex, both of which undergo transmetalation leading to the cross-coupling product. Two distinct mechanistic pathways have been elucidated for stoichiometric reactions of these complexes: (1) transmetalation via an unactivated 6-B-3 intermediate that dominates in the presence of an excess of ligand, and (2) transmetalation via an activated 8-B-4 intermediate that takes place with a deficiency of ligand.
- Thomas, Andy A.,Wang, Hao,Zahrt, Andrew F.,Denmark, Scott E.
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supporting information
p. 3805 - 3821
(2017/03/20)
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- Palladium-Catalyzed Formal Insertion of Carbenoids into Aminals via C-N Bond Activation
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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.
- Qin, Guiping,Li, Lixin,Li, Jiawen,Huang, Hanmin
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supporting information
p. 12490 - 12493
(2015/10/19)
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- Characterization of sites of different thermodynamic affinities on the same metal center via isothermal titration calorimetry
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We investigate the binding thermodynamics of a series of phosphorus ligands to a model compound, PdCl2(solv)2, where solv refers to a molecule of solvent, using isothermal titration calorimetry (ITC). ITC allows for the quantification of the equilibrium binding constant, the binding enthalpy, and the binding stoichiometry all in a single experiment. For systems in which two equivalents of ligand were able to bind to the Pd center, the binding sites on each Pd center in solution showed a different thermodynamic affinity for the same ligand. Changes in binding modes between different phosphorus ligands were due to steric bulk and poor electron-donating ability of such ligands. Our results demonstrate ligand binding was strongly enthalpy-driven due to solvent reorganization, which is the rearrangement of solvent molecules in the bulk solvent and the solvent molecules surrounding the solvated species.
- Moschetta, Eric G.,Gans, Kristina M.,Rioux, Robert M.
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- Donor-free phosphenium-metal(0)-halides with unsymmetrically bridging phosphenium ligands
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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.
- Foerster, Daniela,Nickolaus, Jan,Nieger, Martin,Benko, Zoltan,Ehlers, Andreas W.,Gudat, Dietrich
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p. 7699 - 7708
(2013/07/26)
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- Synthesis, crystal structure and VT-NMR study of cis-[PdCl 2(CNC6H3Me2-2,6)(PPh3)]
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The complex cis-[PdCl2(CNC6H3Me 2-2,6)(PPh3)] has been prepared and fully characterized. Its crystal structure has been determined showing the chloro ligands in cis-disposition. A VT-NMR study shows this complex to be in equilibrium with trans-[PdCl2(PPh3)2] and cis-[PdCl 2(CNC6H3Me2-2,6)2]. The equilibrium is fast at room temperature but at -50 °C all three species are observed in solution in 10:1:1 M ratio. The activation parameters for this equilibrium have been calculated.
- Martinez-Martinez, Antonio Jesus,Chicote, Maria Teresa,Bautista, Delia
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p. 203 - 206
(2012/04/10)
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- Novel phosphite palladium complexes and their application in C-P cross-coupling reactions
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A mono- and a 1,3-bis-phosphite arene ligand based on 2,2′-biphenol have been synthesized in order to study the synthesis of the corresponding palladium(II) complexes starting from different Pd precursors. Novel bis-phosphite palladium complex 1 [PdCl2(L)2] (L = dibenzo[d,f][1,3,2]dioxaphosphepin, 6-phenoxy), C,P-chelate bonded monophosphite palladium complex 2 [Pd(κ2-L)(μ-Cl)]2, and PCP-pincer palladium complex 3 have been prepared from these ligands in promising to excellent yields (50-95%). Additionally, complexes 1 and 3 have been characterized by X-ray crystal structure determinations. The application of 2,6-bis-phosphite pincer palladium(II) complex 3 in C-P cross-coupling between diphenylphosphine-borane and a wide range of various aryl iodides under very mild conditions is reported. Kinetic investigations indicate that 3 merely acts as a pre-catalyst and that Pd nanoparticles are the actual catalytically active species.
- Li, Jie,Lutz, Martin,Spek, Anthony L.,Van Klink, Gerard P.M.,Van Koten, Gerard,Klein Gebbink, Robertus J.M.
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p. 2618 - 2628
(2010/11/21)
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- Oxidative addition of Sn-C bonds on palladium(0): Identification of palladium-stannyl species and a facile synthetic route to diphosphinostannylene- palladium complexes
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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).
- Cabon, Yves,Reboule, Irena,Lutz, Martin,Klein Gebbink, Robertus J. M.,Deelman, Berth-Jan
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p. 5904 - 5911
(2011/01/03)
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- Palladium and molybdenum complexes of the heteroleptic organostannylene[2, 6-(Me2NCH2)2C6H3]SnCl
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The synthesis and molecular structures are reported for the transition metal heteroleptic organo-stannylene complexes {[2,6-(Me2NCH 2)2C6H3]SnCl}(C5H 5)(CO)2MoCl (6) and {[2,6-(Me2NC-H 2)2C6H3]Sn(OAc)}Pd(Cl)[2-(Me 2NCH2)C6H4] (7). It is shown that the intramolecularly coordinated heteroleptic organostannylene [2,6-(Me 2NCH2)2C6H3]SnCl undergoes a redox-type reaction with Pd(PPh3)4 to give cis-[2,6-(Me2NCH2)2C6H 3]SnCl}2PdCl2.
- Martincova, Jana,Jambor, Roman,Schuermann, Markus,Jurkschat, Klaus,Honzicek, Jan,Paz, Filipe A. Almeida
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p. 4778 - 4782
(2011/03/21)
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- New carboalkoxybis(triphenylphosphine)palladium(II) cationic complexes: Synthesis, characterization, reactivity and role in the catalytic hydrocarboalkoxylation of ethene. X-ray structure of trans-[Pd(COOMe)(TsO)(PPh3)2]·2CHCl3
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The cationic complexes trans-[Pd(COOR)(H2O)(PPh3)2](TsO) have been synthesised by reacting cis-[Pd(H2O)2(PPh3)2](TsO)2·2H2O with CO in ROH (R = Me and Et), practically under room conditions, or by methathetical exchange of trans-[Pd(COOMe)Cl(PPh3)2] with Ag(TsO) (R = n-Pr, iso-Pr, n-Bu, iso-Bu, sec-Bu). They have been characterised by IR, 1H NMR and 31P NMR spectroscopies. The X-ray investigation of trans-[Pd(COOMe)(TsO)(PPh3)2] reveals that the palladium center is surrounded in a virtually square planar environment realized by two PPh3 trans to each other, the carbon atom of the carbomethoxy ligand and an oxygen atom of the p-toluensulfonate anion, with two crystallization molecules of CHCl3. The Pd-O-S angle, 151.9 (3)°, is very wide, probably due to the interaction of one CHCl3 molecule with the complex inner core. The carbomethoxy derivatives react with R′OH yielding the corresponding R′ carboalkoxy derivative (R′ = Et, n-Pr and iso-Pr); ethene does not insert into the Pd-COOMe bond; decarbomethoxylation occurs when treated with TsOH/H2O in MeOH at 50 °C. All the carboalkoxy are precursors for the catalytic carboalkoxylation of ethene if used in combination of PPh3 and TsOH, better in the presence of some water. Experimental evidences are more in favor of the so-called "hydride" mechanism rather than the "carbomethoxy" mechanism.
- Amadio,Cavinato,Dolmella,Ronchin,Toniolo,Vavasori
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p. 103 - 110
(2009/04/12)
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- Variable bonding modes of pyrimidine-2-thione in PdII/Pt II complexes [M(η2-N, S-pymS)(η1-S- pymS)(PPh3)] and [M(η1-S-pymS)2(L-L)] (L-L = dppm, dppe)
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Reactions of pyrimidine-2-thione (HpymS) with PdII/Pt IV salts in the presence of triphenyl phosphine and bis(diphenylphosphino) alkanes, Ph2P-(CH2) m-PPh2 (m = 1, 2) have yielded two types of complexes, viz. (a) [M(η2-N, S- pymS)(η1-S- pymS)(PPh 3)] (M = Pd, 1; Pt, 2), and (b) [M(η1-S-pymS) 2(L-L)] {L-L, M = dppm (m = 1) Pd, 3; Pt, 4; dppe (m =2), Pd, 5; Pt, 6}. Complexes have been characterized by elemental analysis (C, H, N), NMR spectroscopy (1H, 13C, 31P), and single crystal X-ray crystallography (1, 2, 4, and 5). Complexes 1 and 2 have terminal η1-S and chelating η2-N, S-modes of pymS -, while other Pd/Pt complexes have only terminal η1-S modes. The solution state 31P NMR spectral data reveal dynamic equilibrium for the complexes 3, 5 and 6, whereas the complexes 1, 2 and 4 are static in solution state.
- Lobana, Tarlok S.,Kaur, Parminderjit,Hundal, Geeta,Butcher, Ray J.,Castineiras, Alfonso
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p. 747 - 753
(2009/04/13)
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- 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
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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.
- Clarke, Matthew L.,Ellis, Dianne,Mason, Kate L.,Orpen, A. Guy,Pringle, Paul G.,Wingad, Richard L.,Zaher, Damien A.,Baker, R. Tom
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p. 1294 - 1300
(2007/10/03)
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- Selective oxidative carbonylation of amines to oxamides and ureas catalyzed by palladium complexes
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A new process for converting secondary amines into N,N,N′,N′- tetraalkyloxamides under CO pressure, catalyzed by homogeneous palladium complexes in the presence of 1,4-dichloro-2-butene (DCB) as an oxidant, has been developed. The mechanism of the oxidative double-carbonylation process, consisting of the oxidation of Pd(0) to Pd(11) with DCB through a β-chloride elimination of the η3-(chloromethyl) allylpalladiuni(11) intermediate, the formation of mono- and bis(carbamoyl)palladium species, and a reductive elimination of the two carbamoyl ligands, is proposed based on studies of the behavior of carbamoylpalladium complexes. When primary amines are employed with DCB as the oxidant, N,N′-dialkyloxamide is catalytically produced, whereas urea is exclusively produced when iodine is used as the oxidant. The reaction of an N-monopropylcarbamoylpalladium complex with propylamine under CO gave N,N′-dipropylurea, whereas a treatment with diethylamine yielded unsymmetrical N,N-diethyl-N′-propylurea, implying the intermediate formation of propyl isocyanate that is converted into the urea upon a reaction with the added amine. A kinetic study on the reaction of chloro-N- propylcarbamoylpalladium with triethylamine suggested a process proceeding through a base-promoted dcprolonalion of the N-monoalkylcarbamoyl ligand to form propyl isocyanate.
- Hiwatari, Kozo,Kayaki, Yoshihito,Okita, Koshi,Ukai, Tomohiro,Shimizu, Isao,Yamamoto, Akio
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p. 2237 - 2250
(2007/10/03)
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- Palladium(II) complexes with benzoxazol-2-ylidene ligands: Crystal structures of trans-chloro(benzoxazol-2-ylidene)-bis(triphenylphosphine) palladium(II) chloride and cis-diiodo(benzoxazol-2-ylidene)(triphenylphosphine) palladium(II)
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The palladium(II) complexes trans-[PdCl(L)(PPh3)2]Cl, 5, and cis-[PdI2(L)PPh3], 7, (L = benzoxazol-2-ylidene) have been synthesized by treatment of the complexes trans-[PdX 2(PPh3)2] (4: X = Cl, 6: X = I) with 2-(trimethylsiloxy)phenyl isocyanide 1, and subsequent hydrolysis of the Si-O bond. The crystal structures of 5 and 7*CH2Cl2 were established by X-ray diffraction. NMR and IR studies indicate, that the unexpected cis-configuration of 7 obtained from trans-[PdI2(PPh 3)2] is not the result of a solution equilibrium between the cis- and the trans-isomers.
- Hahn, F. Ekkehardt,Lügger, Thomas,Beinhoff, Matthias
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p. 196 - 201
(2007/10/03)
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- Palladium-catalyzed oxidative carbonylation of 1-alkynes into 2-alkynoates with molecular oxygen as oxidant
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A new preparative method to produce alkyl 2-alkynoates from 1-alkynes in alcohol under atmospheric pressure of CO at room temperature was developed with palladium-phosphine catalysts, using molecular oxygen as an oxidant. On the basis of the behavior of model complexes such as methoxycarbonylpalladium and alkynylpalladium complexes, we propose a mechanism accounting for the catalytic carbonylation of alkynes through an intermediate having the both methoxycarbonyl and alkynyl ligands that liberates methyl 2-alkynoates and a Pd(0) species on reductive elimination. The oxidation of Pd(0) to Pd(II) species in the presence of a halide ion was confirmed to proceed cleanly with molecular oxygen as the oxidant. On the basis of the findings on homogeneous catalysts, a heterogeneous catalytic system using Pd/C has also been developed.
- Izawa, Yusuke,Shimizu, Isao,Yamamoto, Akio
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p. 2033 - 2045
(2007/10/03)
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- Preparation of the first complexes of bidentate sulfimides; the X-ray crystal structures of [PdBr2{1,4-(PhS{NH})2C6H4}] 2, [PdCl2{1,2-(PhS{NH})(PhS)C6H4}] and trans-[PdCl2{1,2-(PhS{NH})(PhS)C6H4} PPh3]
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Reaction of [PPh4]2[Pd2X6] (where X = Cl, Br or I) with 1,4-(PhS{NH})2C6H4 (1) in dichloromethane results in the formation of [Pd{1,4-(PhS{NH})2C6H4}X2] 2 (2). X-ray crystallography (performed using a synchrotron source) confirms that in the case where X = Br (2a) both the bis-sulfimides act as bridging ligands through N-Pd bonds producing an 18-membered ring system linking the four sulfur atoms into an almost perfect square. Changing the reaction solvent to methanol/dichloromethane results in the formation of a polymeric material. Reaction of [PdCl2(PhCN)2] with 1,2-(PhS{NH})-(PhS)C6H4 (3) results in the formation of [PdCl2{1,2-(PhS{NH})(PhS)C6H4}] (4) in which 3 acts as a bidentate ligand, bound by N-Pd and S-Pd bonds to form a unique MSCCSN metallacycle. The Pd-S bond is broken upon reaction with one equivalent of PPh3, generating trans-[PdCl2{1,2-(PhS{NH})(PhS)C6H4} PPh3] (5); further reaction with PPh3 results in complete removal of 3 from the system and formation of trans-[PdCl2(PPh3)2]. Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003.
- Elsegood, Mark R. J.,Holmes, Kathryn E.,Kelly, Paul F.,MacLean, Elizabeth J.,Parr, Jonathon,Stonehouse, Julia M.
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p. 120 - 127
(2007/10/03)
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- Synthesis and reactivity of phenoxycarbonyl palladium complex: Relevant to the mechanism of oxidative carbonylation of phenol
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Phenoxycarbonyl palladium complex was synthesized and its reactivity was investigated relevant to the mechanism of the palladium-catalyzed oxidative carbonylation of phenol to produce diphenyl carbonate (DPC). The phenoxycarbonyl palladium complex PdCl(CO2Ph) (PPh3)2 (1) was synthesized by oxidative addition of phenyl chloroformate to Pd(PPh3)4. Complex 1 could be isolated as single crystals and characterized by X-ray crystallography. The thermolysis of 1 resulted in DPC formation, although degradation of the PPh3 ligand to PhCl and PhCO2Ph simultaneously occurred. PdCl2(PPh3)2 was a major newly formed palladium species. An efficient DPC formation was observed for the reaction of 1 with phenyl chloroformate. On the other hand, the reaction of 1 with sodium phenoxide (one equivalent) proceeded at -20°C causing the instant formation of a new species assignable to Pd(OPh)(CO2Ph)(PPh3)2 (2) as judged by NMR (1H, 13C{1H}, and 31P{1H}) spectroscopy; the nucleophilic attack by phenoxide preferentially took place on the palladium center rather than on the carbonyl group. When the reaction mixture was heated, DPC was produced probably via the reductive elimination from 2. These results as well as the previous finding that diaryl carbonate is formed from palladium diaryloxide by carbonylation and subsequent reductive elimination suggest that Pd(OPh)(CO2Ph) L2 is the final intermediate toward DPC: the reductive elimination requires a relatively high temperature.
- Yasuda, Hiroyuki,Maki, Noriko,Choi, Jun-Chul,Sakakura, Toshiyasu
-
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- Activation of σ(C-H) bonds of [Fe{(η5-C5 H4)-C(Me)=N-N=C(H)(C6H3-2,6-R)} 2] (with R=Cl or H) promoted by palladium(II)
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The synthesis, characterisation and the study of the reactivity of the novel and bifunctional ferrocenyl Schiff bases [Fe{(η5-C5H4)-C(Me)=N-N=C(H) (C6H3-2,6-R2)}2] (with R=Cl or H) with palladium(II) salts under different experimental conditions are reported. The treatment of Na2 [PdCl4], Na(CH3COO)·3H2O and the corresponding ligand [Fe{(η5 -C5H4)-C (Me)=N-N=C(H)(C6H3 -2,6-R2 }2] (with R=Cl or H) (in a 2:2:1 molar ratio) in methanol for 6 days followed by the addition of triphenylphosphine (PPh3), and a SiO2 column chromatography, allowed the isolation of the two isomers (meso- and D,L - forms) of the heterotrimetallic complexes of general formula [Pd2{Fe[(η5-C5 H3)-C(Me)=N-N-C(H)(C6H5-2,6- R2)]2}Cl2(PPh3)2], (with R = Cl or H).
- López, Concepcíon,Bosque, Ramón,Arias, Javier,Evangelio, Emilia,Solans, Xavier,Font-Bardía, Mercè
-
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- Transition metal complexes containing P(C6H5)(C6H4Cl-2)2. The effect of added Lewis bases as a probe for substitution reactions occurring in ambient temperature Suzuki couplings catalyzed by Pd/P(C6H5)(C6H4Cl-2)2
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The reactivity of the d8 transition metal complexes, [NiBr2(CH3OCH2CH2OCH 3)] and MCl2L2 (M=Pd, Pt; L=CH3CN; L2=1,5-cyclooctadiene), towards P(C6H5)(C6H4Cl-2)2 (1) was investigated. While treatment of [PdCl2(cod)] with 2 equiv of 1 resulted in displacement of the weakly coordinating cyclooctadiene and formation of [PdCl2(P(C6H5)(C6H 4Cl-2)2)2], analogous reactions with [PtCl2(cod)] afforded the monosubstituted species [PtCl2(cod)(P(C6H5)(C6H 4Cl-2)2)]. The disubstituted complex [PtCl2(P(C6H5)(C6H 4Cl-2)2)2] was successfully obtained by treatment of [PtCl2(NCCH3)2] with 2 equiv of 1. However, attempts to react 1 with [NiBr2(CH3OCH2CH2OCH 3)] were unsuccessful. The chlorinated triphenyl phosphine is quite labile and is readily displaced from [PdCl2(P(C6H5)(C6H 4Cl-2)2)2] by various Lewis bases including nitrogen containing ligands such as 2,2′-bipyridine. The molecular structure of trans-[PdCl2(P(C6H5)(C6H 4Cl-2)2)2] was determined by X-ray diffraction and represents the first molecular structure determination of a transition metal complex containing 1. This complex crystallizes in the monoclinic space group P21/n with a=10.3928(3) ?, b=16.0102(4) ?, c=13.1884(4) ?, β=90.714(2)°, and Z=4. Key geometric parameters include Pd-Cl(1)=2.309(1) ?, Pd-P(1)=2.334(1) ?; Pd-P(1)-C(7)=118.3(2)°, Pd-P(1)-C(1)=115.3(2)°, C(1)-C(6)-Cl(2)=120.7(4)° and Cl(1)-Pd-P(1)=85.86(4)°.
- Stone, Joshua J.,Stockland Jr., Robert A.,Rath, Nigam P.
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p. 236 - 240
(2008/10/08)
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- Triphenyl-phosphine and -arsine analogues which facilitate the electrospray mass spectrometric analysis of neutral metal complexes
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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.
- Decker, Corry,Henderson, William,Nicholson, Brian K.
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p. 3507 - 3513
(2007/10/03)
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- On the oxidative addition of 1-Halogenalk-1-ynes - Synthesis and structure of phenylalkynylpalladium complexes
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[Pd(PPh3)4] (2) reacts with IC≡CPh and ClC≡CPh in the sense of an oxidative addition to give trans[Pd(C≡CPh)X(PPh3)2] (X = I: 3 a, X = Cl: 3 b). As side products trans-[PdX2(PPh3)2] (X = I: 4 a, X = Cl: 4 b; a and 3 b were characterized by NMR (1H, 13C, 31P) and IR spectroscopies as well as by X-ray single-crystal structure analyses. In the crystals of 3 a and 3 b isolated molecules were found. The Pd-C≡C-Ph unit is linear in 3 a and approximately linear in 3 b [Pd-C≡C 174.2(6)°, C≡C-C 179,0(7)°].
- Weigelt, Michael,Becher, Diana,Poetsch, Eike,Bruhn, Clemens,Steinborn, Dirk
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p. 1542 - 1547
(2008/10/08)
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- On the mechanism of the hydrogen transfer from H2O-CO to γ-keto-α-hydroxy carboxylic acids to yield γ-keto acids catalyzed by a PdCl2(PPh3) 2 precursor in combination with hydrochloric acid
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The catalytic system PdCl2(PPh3)2-HCl is highly active and selective in the hydrogen transfer reaction from H2O-CO to PhCOCH2CHOHCOOH which yields the corresponding γ-keto acid PhCOCH2CH2COOH, with concomitant evolution of CO2. An increase of temperature, pressure of carbon monoxide and catalyst concentration have a beneficial effect on the reaction rate, which appears to be of the first order in the substrate and passes through a maximum when varying the concentration of HCl. It is proposed that one important function of HCl is to give rise to chloride PhCOCH2CHClCOOH which interacts with a palladium hydride that takes origin from the decarboxylation of a species having a Pd-COOH moiety, which in turn results from the interaction of H2O and CO on the metal center. The yield passes through a maximum on increasing the concentration of H2O. This trend is attributed to the fact that, on one hand, H2O favors the formation of the Pd-COOH species, while, on the other hand, it may compete with other reacting molecules for coordination to the metal center. Moreover, H2O does not favor the formation of the chloride. When employed in relatively high concentration, the catalyst precursor has been recovered as a complex of palladium(0), Pd3(CO)3(PPh3)3 or Pd(CO)(PPh3)3, the latter in the presence of PPh3. The reduction to palladium(0) takes place only in the presence of H2O and is likely to occur via the intermediacy of a Pd-COOH species, which after CO2 evolution gives the reduced complex probably via reductive elimination of HCl from the hydride intermediate trans-PdHCl(PPh3)2. Moreover, PhCOCH=CHCOOH in combination with HCl (equivalent to PhCOCH2CHClCOOH) reacts with Pd(CO)(PPh3)3 to give the hydrogenated product PhCOCH2CH2COOH and PdCl2(PPh3)2. On the basis of these results, and knowing that HCl reacts with Pd(CO)(PPh3), to give the hydride PdHCl(PPh3)2, it is proposed that the catalytic cycle proceeds through the following steps: (i) H2O and CO interact with the metal center of the precursor yielding a Pd-COOH species, (ii) this gives off CO2 with formation of a hydride, (iii) this interacts with chloride PhCOCH2CHClCOOH to yield the product PhCOCH2CH2COOH and the palladium(II) precursor back to the catalytic cycle.
- Cavinato,Toniolo
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- Isolation of a postulated intermediate in the Stille reaction. Synthesis of 2-arylazoarylphosphonium salts via C-P coupling. Synthesis of acetone complexes of palladium(II).
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PPh3 and aqueous HClO4 react with an acetone solution of [Pd(C6H4N=NPh-2) (O, O-acac)] (Hacac=acetylacetone; 1:2:7) 1a or [Pd{C6H3(N=NTo)-2,Me-5′}(O,O-acac)] (To= C6H4Me-4; 1:1:7) 1b to give [Pd(C6H4N=NPh-2)(PPh3)(acetone)]ClO4 2a or [Pd(C6H3N=NTo)-2,Me-5′}(PPh 3)(acetone)]ClO4 2b, respectively. They also react with a dichloromethane solution of 1b to afford a mixture of the phosphonium salt [Ph3P{C6H3(N2To)-2,Me-5}]ClO 4 3b and the complex [Pd(O,O-acac)(PPh3)2]ClO4 4. Compounds 2a, 2b or 4 have also been prepared directly by reacting [Pd(R)(μ-Cl)]2 (R=C6H4N=NPh-2 or C6H3(N=NTo)-2,Me-5′)], PPh3 and AgClO4 in acetone or [PdCl2(PPh3)2] with NaClO4·H2O and Tl(acac), respectively. The phosphonium salts [Ph3P{C6H4(N2Ph)-2}]ClO4 3a or 3b can be prepared by reacting complexes 2a or 2b, respectively, with PPh3. The structures of 2a, 3b and 4 have been determined by X-ray diffraction methods. Complex 2a crystallizes in the triclinic space group P1 with Z=2 in a unit cell of dimensions a=9.588(6), b=10.966(5), c=15.464(8) A, α=95.82(1), β=99.54(1), γ=91.21(1)°. Compound 3b crystallizes in the monoclinic space group P21/n with Z=4 in a unit cell of dimensions a=10.523(4), b=28.102(11), c=10.028(5) A, β=94.41(1)°. Compound 4 crystallizes in the monoclinic space group P21 with Z=4 in a unit cell of dimensions a=9.763(5), b=33.465(9), c=12.026(5) A, β=103.06(2)°. The structures have been solved from diffractometer data by Patterson and Fourier mehods and refined by full-matrix least squares on the basis of 5539 (2a), 1873 (3b) and 6798 (4) observed reflections to R and Rw values of 0.0584 and 0.0645 (2a), 0.0617 and 0.0642 (3b), 0.0410 and 0.0478 (4). In 2a the Pd atom is coordinated in a square planar fashion by the P atom from the PPh3 ligand, by the O(1) atom from the acetone molecule, and by the N and C atoms from the chelating C6H4N=NPh-2 ligand. The structure of the phosphonium salt 3b shows the C-P bond coupling of C6H4(N2To)-2,Me-5′ with PPh3. The Pd atom in 4 is in a square planar arrangement involving two P atoms from the PPh3 ligands and two O atoms from the chelating acac ligand. CNRS-Gauthier-Villars.
- Vicente, Jose,Arcas, Aurelia,Bautista, Delia,Tiripicchio, Antonio,Camellini, Marisa Tiripicchio
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p. 345 - 356
(2008/10/08)
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- New alkoxycarbonyl complexes of palladium (II) and their role in carbonylation reactions carried out in the presence of an alkanol
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The new complexes of general formula trans-Pd(COOR)ClL2 =PPH3 R=Et, n-Pr, iso-Pr, n-Bu, iso-Bu, 2-ethoxyethyl, cyclopentyl, cyclohexyl; L=1,2-diphenylphosphinoethane, R=Et) are prepared reacting trans -PdCl2L2, suspended in an alkanol, under 10-50 atm of carbon monoxide, at 50-70°C, in presence of a base such as a trialkylamine or a carboxylic acid anion. They have been characterized by IR, 1H and 31P NMR spectroscopy. The complexes with R=Me and Et show two absorption bands centered at ca. 1650 cm-1, which are probably due to conformational isomers with cis and trans geometry. The other show only one band at ca. 1650 cm-1. The 1H NMR and 31P NMR spectra of all the monophosphine complexes show that only one isomer is present in solution. Instead, for the diphosphine ethoxycarbonyl complex the 1H NMR spectra suggest that two isomers are present, in the ratio of ca. 1:1, as confirmed by decoupling experiments. The two isomers may take origin from different orientation of the alkoxycarbonyl ligand with respect to the asymmetrical metal centre, because of hindered rotation around the Pd-C bond due to the partial double bond character. The R group of the alkoxycarbonyl ligand can be exchanged with a different R' group by reacting the Pd(COOR)Cl(PPh3)2 complex with an excess of R'OH. The reaction is practically quantitative when R is bulkier than R'. The alkoxycarbonyl complexes react with the corresponding alkanol, in the presence of a base such as a trialkylamine, at 90-100°C, under carbon monoxide, yielding Pd(0) carbonyl-phosphine complexes with formation of dimethyl carbonate in an almost quantitative yield. They react also with water giving off CO2 and yielding Pd(0) complexes. The reaction is promoted by an acid of a noncoordinating anion such as HBF4. Instead, the reaction with HCl yields the corresponding dichloride of Pd(II), beside carbon monoxide and the corresponding alkanol. The role of these complexes in catalytic alkoxycarbonylation reactions is discussed.
- Bertani, R.,Cavinato, G.,Toniolo, L.,Vasapollo, G.
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p. 165 - 176
(2008/10/08)
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- Novel Basic Ligands for the Homogeneous Catalytic Carbonylation of Methanol, XXVIII. - Synthesis, Properties and Fluxional Behavior of (Ether-Phosphine)palladium Complexes
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Cl2Pd(COD) (1) (COD = 1,5-cyclooctadiene) reacts with 1 equiv. of the (ether-phosphine) ligand Ph2P-D (2a-c) to give the dimeric complexes 2 (3a-c) (P-D = η1-P-coordinated).According to the field-desorption mass spectra which show only one peak for the monomeric moieties ClPd(Ph2P-D), 3a-c have a very weak Pd2Cl2 bridge. trans-Cl2Pd(Ph2P-D)2 (4a-c) is obtained either from 3a-c and 2a-c by cleaving the Pd2Cl2 bridge or from 1 and 2 equiv. of the ligands 2a-c. 4c crystallizes in the monoclinic spacegroup P21/c with Z = 2.AgClO4 selectively abstracts one Cl- ligand from 4a-c which results in the formation of the cationic complexes D)(Ph2P-D)PdCl>+ (5a-c) (PD = η2-D,P-coordinated) containing one chelated and one η1-P-bonded (ether-phosphine) ligand. 5a-c show fluxional behavior which is demonstrated by temperature-dependent 31P-NMR investigations.The coalescence points have been determined and are at 253 (5a), 303 (5b), and 283 K (5c).The activation enthalpies ΔGexcit. are estimated at 48, 58, and 54 kJ/mol.The abstraction of the second Cl- ligand from 5a-c succeeds only in the presence of AgSbF6 yielding the dicationic bis(chelate) complexes D)2Pd>2+ (6a-c).The latter are also obtained from 4a-c and AgSbF6.The hydrogenating properties of 3a-c and 4a-c toward 1-hexyne are investigated in comparison with trans-Cl2Pd(Ph2PCH2CH2CH3)2.
- Lindner, Ekkehard,Speidel, Robert,Fawzi, Riad,Hiller, Wolfgang
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p. 2255 - 2260
(2007/10/02)
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- Transition-metal-promoted cyclization reactions of isocyanide ligands. Synthesis of cyclic aminooxycarbene complexes of platinum(II) and X-ray structure of trans -{(PPh3)2Pt[CN(C6H4-p-Me)CH 2CH2O]Br}BF4
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Electrophilic isocyanide CNR ligands in cationic Pt(II) complexes of the type trans-[(PR′3)2Pt(CNR)Cl]BF4 (I) (PR′3 = PPh3, PMe2Ph; R = p-MeOC6H4, p-MeC6H4, p-NO2C6H4, Me, C6H11) are converted to the corresponding 5-membered cyclic aminooxycarbene derivatives trans-{(PR′3)2Pt[CN(R)CH2CH 2O]X}BF4 (II) (X = Cl, Br) by reaction in THF with 2-bromoethanol in the presence of n-BuLi. These reactions are likely to proceed by nucleophilic attack of the alkoxide on the isocyanide carbon atom to give an imidoyl intermediate, which cyclizes intramolecularly to yield the carbene products. The less sterically hindered CNMe and aryl isocyanide ligands in I are converted in a few minutes to the final products II in ca. 70-90% yield; the more bulky CNC6H11 derivative gives only a 25% yield. The t-BuNC ligand in the complex trans-[(PPh3)2Pt(CN-t-Bu)Cl]BF4 does not react at all, nor does p-MeOC6H4NC in trans-[(PCy3)2Pt(CNC6H 4-p-OMe)Cl]BF4 with bulky PCy3 ligands. Treatment of cis-Cl2Pt(CNC6H4-p-OMe)2 with 2 equiv of 2-bromoethoxide gave the bis(aminooxycarbene) Br2Pt[CN(C6H4-p-OMe)CH2CH 2O]2. The Pt(II)-cyclic aminooxycarbenes II were characterized by their elemental analysis and IR, 1H NMR, and 31P NMR spectra. An X-ray-determined structure of trans-{(PPh3)2Pt[CN(C6H 4-p-Me)CH2CH2O]Br}BF4, space group P21/a, a, = 12.175 (2) ?, b = 26.137 (3) ?, c = 13.274 (4) ?, β = 91.61 (2)°, and Z = 4, was refined to R = 0.039 (Rw = 0.044) for 5325 independent reflections. The coordination geometry around the Pt(II) atom is square planar with the carbene ligand perpendicular to the plane. The cyclic aminooxycarbene ligand is planar with C(sp2)-N and C(sp2)-O bond distances of 1.30 (1) and 1.33 (1) ?, indicating significant π-bonding between the nitrogen, oxygen, and carbene carbon.
- Michelin, Rino A.,Zanotto, Livio,Braga, Dario,Sabatino, Piera,Angelici, Robert J.
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- Complexes of Functional Phosphines. Part 11. β-Ketophosphine Complexes of Nickel, Palladium, and Platinum. Crystal Structures of trans-
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The synthesis and spectroscopic properties (1H and 31P n.m.r., i.r.) of complexes containing the β-ketophosphine Ph2PCH2C(O)Ph (HL) are described.In , (4), (5), and 2> (6), HL behaves as a P-bonded monodentate ligand whereas in the cationic complexes 2 and 2>2 it acts as a P, O chelate.The crystal structures of (1) and (3) have been determined using single-crystal X-ray diffraction methods.Compound (1) crystallises in space group P21/n, with a=10.079(3), b=11.510(3), c=15.411(3) Angstroem, β=93.42(2) deg, and Z=2.Compoumd (3) crystallises in space group P21/c, with a=9.283(1), b=10.261(1), c=19.318(1) Angstroem, β=96.20(1) deg, and Z=2.The structures have been refined to R 0.050 (R' 0.060) for (1) and to R 0.032 (R' 0.041) for (3).The geometries of these complexes are essentially identical although the ν(CO) frequencies of these complexes are significantly different -1 for (1) and 1 620 cm-1 for (3)>; the nickel atom occupies a centre of symmetry and has thus a square-planar environment.Although the ketone group is bent towards the nickel atom, no significant Ni-O bonding interaction occurs, as deduced from the Ni-O distances .In refluxing toluene (1), (4), or (5) lead to the phosphine-phosphinite complexes cis- (M=Ni, Pd, or Pt).Treatment of (1), (4), or (5) with base gives the enolato-complexes cis- (M=Ni, Pd, or Pt).Reaction of (6) with NaH affords the binuclear complex .The latter reacts with PPh3 to give cis-, and with Ph2PCH2CH2PPh2-TIPF6 to give .The P-O coupling products (R=Cl or Ph) are obtained by reaction of the complex with PCl3 and PPhCl2 respectively, and shown to have a five-co-ordinate structure.The square-planar P,P,P complex results from reaction of with TIPF6.
- Braunstein, Pierre,Matt, Dominique,Nobel, Dominique,Balegroune, Fadila,Bouaoud, Salah-Eddine,et al.
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p. 353 - 362
(2007/10/02)
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- 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)
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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.
- Porta, Francesca,Pizzotti, Maddalena,Monica, Gerolamo La,Finessi, Luis A.,Cenini, Sergio,et al.
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p. 2409 - 2414
(2007/10/02)
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- Cyclopentadienyl-Ruthenium and -Osmium Chemistry. XXII. Synthesis, X-Ray Structure and Some Reactions of RuCl(PPh3)(η1-Ph2PCH2PPh2)(η-C5H5), Containing a Monodentate CH2(PPh2)2 Ligand
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Stoichiometric amounts of RuCl(PPh3)2(η-C5H5) and dppm react in refluxing C6H6 to give RuCl(PPh3)(η1-dppm)(η-C5H5), which has been fully characterized by an X-ray study (triclinic, space group P, a 22.377(6), b 9.913(2), c 9.826(3) Angstroem, α 70.46(2), β 78.72(2), γ 80.40(2) deg, Z 2) in which 3299 data were refined to R 0.046, R' 0.052.Structural parameters are similar to those of other RuX(PR3)2(η-C5H5) complexes.The chloro complex was converted was converted into 2-dppm)(η-C5H5)>+ salts; the other PPh3 ligand can be replaced by a second dppm ligand to give +, which contains both mono- and bidentate dppm ligands.Alkylation of the uncoordinated phosphorus with Mel is accompanied by halogen exchange to give I, while reactions with a variety of transition metal complexes result in abstraction of PPh3 and formation of RuCl(dppm)(η-C5H5).
- Bruce, Michael I.,Humphrey, Mark G.,Patrick, Jennifer M.,White, Allan H.
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p. 2065 - 2072
(2007/10/02)
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- REACTIONS OF A CHELATED ALKYLPALLADIUM COMPOUND
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The chemistry of the compound (V, R = CH(CO2Et)2) with nucleophilic (PPh3, pyridine, CO) and electrophilic (H2, HCl) reagents is studied. although the nucleophiles cleave the chloride bridges, they do not readily disrupt the Pd-N bond, and both V and its adducts are very stable with respect to decomposition via olefin elimination.As expected, however, H2 and HCl cleave the Pd-C bond to give CH3CHRCH2NMe2 and either Pd metal or a palladium chloride complex, respectively.
- Weinberg, E. L.,Hunter, B. K.,Baird, M. C.
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- Bis(arylazo-oximato)palladium(II); Synthesis, Palladium-Nitrogen Bond Lability, and Redox Activity
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The synthesis and characterisation of the title complex, , and related mixed-ligand complexes including (A = ortho-metallated azobenzene) are described.The mass spectrum of reveals peaks corresponding to loss of oximato-O and NO from the parent ion.Gaseous HCl cleaves the Pd-N(oxime) bond selectively.Triphenylphosphine cleaves one or both Pd-N(azo) linkages giving and unstable which is also produced by oxidative addition of HL to .In the unidentate and bidentate L groups scramble rapidly at 308 K but slowly at 233 K (1H n.m.r.).Bidentate phosphine and phosphinoarsine cleave the two Pd-N(azo) bonds simultaneously.Unidentate amines, when present in very large excess, produce unstable in which one L is unidentate.Addition of X2 (X= Cl or Br) yields the unstable palladium(IV) complex which is readily reduced to halogeno-bridged palladium(II) species.A cyclic-voltammetric study of the one-electron quasi-reversible reduction of , , etc. at a platinum electrode is briefly reported.
- Bandyopadhyay, Pinaki,Mascharak, Pradip K.,Chakravorty, Animesh
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p. 623 - 627
(2007/10/02)
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- Selective Cleavage of the Two Types of Pd-N Bonds in Di-μ-halogeno-bis
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Triarylphosphines split the halogen bridge of the title complex and also open the arylazo-oximato chelate ring at the azo-end.In solution an equilibrium exists between the closed-ring and open-ring species.The equilibrium constants are reported.Bidentate phosphine and phosphinoarsine simultaneously split the bridge and cleave the Pd-N(azo) bond.Anhydrous HCl gas protonates the oximato-group with its concomitant displacement by Cl-ion; in effect the Pd-N(oxime) bond is selectively cleaved.
- Mascharak, Pradip K.,Chakravorty, Animesh
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p. 1698 - 1702
(2007/10/02)
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