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Pd Complex (pd + complex)

Distribution by Scientific Domains

Chemistry	88%

Distribution within Chemistry

General & Introductory Chemistry	65%
Organic Chemistry	12%

Selected Abstracts

Formation of (,-Alkenyl)- and (,-Vinylidene)palladium and -platinum Complexes by Oxidative Addition of 4,4-Dichloro-1,1-diphenyl-2-azabuta-1,3-diene , The Molecular Structure of an Unusual Asymmetric (,-Vinylidene)Pd,Pd Complex

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 3 2003
Michael Knorr
Abstract 4,4-Dichloro-1,1-diphenyl-2-azabuta-1,3-diene (1) oxidatively adds to [Pd(PPh3)4] and [Pt(C2H4)(PPh3)2] giving rise to the ,-alkenyl complexes trans -[MCl{[C(Cl)=C(H),N=CPh2]}(PPh3)2] (2a: M = Pd; 2b: M = Pt). When 1 is treated with [Pd(PPh3)4] in a 1:2 ratio in refluxing toluene, the dimetallic ,-vinylidene complex [(PPh3)ClPd{,-[C=C(H),N=CPh2]}PdCl(PPh3)2] (3) is formed. In this fluxional compound, a PPh3 ligands migrates in a reversible manner between the two Pd centers. Substitution of the PPh3 ligands of 3 by 2 equiv. of Ph2PCH2PPh2 affords the A-frame complex [ClPd(,-dppm)2{,-[C=C(H),N=CPh2]}PdCl] (4). (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003) [source]

ChemInform Abstract: Synthetic Design of Carbonyl-Group-Containing Compounds Based on C,O Bond Cleavage Promoted by Pd Complexes.

CHEMINFORM, Issue 16 2002
Akio Yamamoto
Abstract ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 100 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a "Full Text" option. The original article is trackable via the "References" option. [source]

Cyclopolymerization and Copolymerization of Functionalized 1,6-Heptadienes Catalyzed by Pd Complexes: Mechanism and Application to Physical-Gel Formation

CHEMISTRY - A EUROPEAN JOURNAL, Issue 29 2010
Sehoon Park Dr.
Abstract Cationic Pd complexes, prepared from [PdCl(ArNC12H6NAr)(Me)] and Na[B{3,5(CF3)2C6H3}4] (NaBARF), catalyze the cyclopolymerization of 4,4-disubstituted 1,6-heptadienes. The polymers produced contain a trans -fused five-membered ring in each repeating unit. NMR spectroscopy and FAB mass spectrometry of the polymers formed indicated that the initiation end of the chain contains either the cyclopentyl group derived from the preformed Pd,monomer complex or a hydrogen atom left on the Pd center by the chain-transfer reaction. The stable cyclopentylpalladium species are involved in both initiation and propagation steps and undergo isomerization into (cyclopentylmethyl)palladium species followed by the insertion of a CHCH2 bond of a new monomer molecule into the PdCH2 bond. Copolymerization of 1,6-heptadiene derivatives with ethylene, catalyzed by the Pd complexes, yields polymers that contain trans five-membered rings and branched oligoethylene units. Copolymerization of isopropylidene diallylmalonate with 1-hexene affords a polymer with 26,% diene incorporation. The copolymerization consumes 1-hexene more readily than isopropylidene diallylmalonate, although gel permeation chromatography and NMR spectroscopy of the polymers produced show the formation of copolymers rather than of a mixture of homopolymers. Polymerization of 1-hexene initiated with a Pd,barbiturate complex and terminated with 5-allyl-5-hexylpyrimidine-2,4,6(1H,3H,5H)-trione/Et3SiH leads to polyhexene with barbiturate moieties at both terminal ends. Addition of 5-hexyl-2,4,6-triaminopyrimidine to a toluene solution of the telechelic poly(1-hexene) converts the solution into gel. [source]

Chelate [2-(Iminoethyl)pyridine N -oxide]metal Complexes , Synthesis and Structural Comparison with Their Chemically Related 2-(Iminoethyl)pyridine-Derived Systems

EUROPEAN JOURNAL OF INORGANIC CHEMISTRY, Issue 2 2006
Katrin Nienkemper
Abstract The N,O-chelate ligands 2-(iminoethyl)pyridine N -oxide (2a) and 2-(iminoethyl)-6-isopropylpyridine N -oxide (2b) were prepared by conventional synthetic routes, the latter involving a variant of the Reissert,Henze reaction. Treatment of 2a with FeCl2 resulted in a deoxygenation reaction of the ligand and formation of the salt [bis{2-(iminoethyl)pyridine}FeCl]+[FeCl4], (18a). In contrast, the reaction of 2a with PdCl2 or CoCl2 cleanly furnished the six-membered chelate [,N,O -2(iminoethyl)pyridine N -oxide]MCl2 complexes (19a, M = Pd) or (20a, M = Co), respectively, which were both characterised by X-ray diffraction. Treatment of 2b with [NiBr2(dme)], followed by crystallisation from THF, gave the complex [(,N,O - 2b)NiBr2(THF)] (21b), which features a distorted trigonal-bipyramidal coordination geometry of the central metal atom. The reaction of 2a with [NiBr2(dme)] gave the structurally related complex [(,N,O - 2a)NiBr2(,O - 2a)] (21a). The N,O-chelate Pd complex 19a was shown to be an active catalyst for the Suzuki coupling reaction. The ligand systems 2a,b and their related 2-(iminoethyl)pyridines 3a,b and a variety of metal complexes of ligands 3 were also prepared and characterised for comparison by X-ray diffraction. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2006) [source]

Asymmetric hydrogenation ofo -Cresol andm -Cresol catalyzed by silica-supported methylcellulose,L-alanine,Pd complex

POLYMERS FOR ADVANCED TECHNOLOGIES, Issue 11-12 2001
Kai Huang
Abstract Silica-supported methylcellulose,L-alanine,palladium complex (SiO2 -MC,LA,Pd) has been prepared and found to be a high optically active catalyst for asymmetric hydrogenation of o -cresol and m -cresol to give (S)-2-methylcyclohexanone and (R)-3-methylcyclohexanone, respectively, at 25,°C and under an atmospheric hydrogen pressure. The optical yields of (S)-2-methylcyclohexanone and (R)-3-methylcyclohexanone amounted to 91.5 and 68.5%, respectively, when optimum Pd content in SiO2 -MC,LA,Pd complex, reaction temperature and solvent were selected. SiO2 -MC,LA,Pd catalyst also has shown high stability. The optical yields for (S)-2-methylcyclohexanone and (R)-3-methylcyclohexanone were kept over 90 and 60%, respectively, when the catalyst was reused several times. Moreover, SiO2 -MC,LA,Pd complex is an economical catalyst. The methylcellulose is an abundant natural biopolymer and the procedure for preparation of the complex is very simple. Copyright © 2001 John Wiley & Sons, Ltd. [source]

More examples of the 15-crown-5...H2O,M,OH2...15-crown-5 motif, M = Al3+, Cr3+ and Pd2+

ACTA CRYSTALLOGRAPHICA SECTION B, Issue 2 2010
Maxime A. Siegler
Five structures of co-crystals grown from aqueous solutions equimolar in 15-crown-5 (or 15C5) and [M(H2O)6](NO3)n, M = Al3+, Cr3+ and Pd2+, are reported. The hydrogen-bonding patterns in all are similar: metal complexes including the fragment trans -H2O,M,OH2 alternate with 15C5 molecules, to which they are hydrogen bonded, to form stacks. A literature survey shows that this hydrogen-bonding pattern is very common. In each of the two polymorphs of the compound [Al(H2O)6](NO3)3·15C5·4H2O there are two independent cations; one forms hydrogen bonds directly to the 15C5 molecules adjacent in the stack, while the other cation is hydrogen-bonded to two water molecules that act as spacers in the stack. These stacks are then crosslinked by hydrogen bonds formed by the three nitrate counterions and the three lattice water molecules. The hydrogen-bonded stacks in [Cr(H2O)5(NO3)](NO3)2·1.5(15C5)·H2O are discrete rather than infinite; each unit contains two Cr3+ complex cations and three 15C5 molecules. These units are again crosslinked by the uncoordinated nitrate ions and a lattice water molecule. In [Pd(H2O)2(NO3)2]·15C5 the infinite stacks are electrically neutral and are not crosslinked. In [Pd(H2O)2(NO3)2]·2(15C5)·2H2O·2HNO3 a discrete, uncharged unit containing one Pd complex and two 15C5 molecules is `capped off' at either end by a lattice water molecule and an included nitric acid molecule. In all five structures the infinite stacks or discrete units form an array that is at least approximately hexagonal. [source]

Tetraalkylammonium-Free Heck Olefination of Deactivated Chloroarenes by Using a Macrocyclic Catalyst Precursor

CHEMISTRY - A EUROPEAN JOURNAL, Issue 8 2010
Christoph Röhlich Dipl.-Chem.
Palladium reservoir: A macrocyclic dinuclear Pd complex is applied to the Heck coupling of strongly deactivated aryl chlorides. The complex serves as a very stable precatalyst, which releases active Pd under normal reaction conditions (see scheme). The controlled release and recapture of active Pd provides sufficient stabilization to supersede the addition of tetrabutylammonium bromide. Quantitative conversions can be achieved under additive-free conditions. [source]

Identification of a Highly Efficient Alkylated Pincer Thioimido,Palladium(II) Complex as the Active Catalyst in Negishi Coupling

CHEMISTRY - A EUROPEAN JOURNAL, Issue 17 2009
Jing Liu Dr.
Abstract PdIIate complex: A novel alkylated pincer thioimido,Pd complex generated from a catalyst precursor and basic organometallic reagents (RM) was observed by in situ IR, 1H,NMR, and 13C,NMR spectroscopies for the first time and proved to be the active catalyst in stoichiometric and catalytic reactions of aryl iodides with RM (see scheme). The catalyst, as an electron-rich PdII species, promoted the Negishi coupling of aryl iodides and alkylzinc reagents with high efficiency, even at low temperatures (0 or ,20,°C). The induction period of Negishi coupling catalyzed by pincer thioamide,palladium complex 1 was investigated. A heterogeneous mechanism was excluded by kinetic studies and comparison with Negishi coupling reactions promoted by Pd(OAc)2/Bu4NBr (a palladium,nanoparticle system). Tetramer 2 was isolated from the reaction of 1 and organozinc reagents. Dissociation of complex 2 by PPh3 was achieved, and the structure of resultant complex 8 was confirmed by X-ray diffraction analysis. A novel alkylated pincer thioimido,PdII complex, 7, generated from catalyst precursor 1 and basic organometallic reagents (RM), was observed by in situ IR, 1H,NMR, and 13C,NMR spectroscopy for the first time. The reaction of 7 with methyl 2-iodobenzoate afforded 74,% of the cross-coupled product, methyl 2-methylbenzoate, together with 60,% of PdII complex 2. Furthermore, the catalyst, as an electron-rich PdII species, efficiently promoted the Negishi coupling of aryl iodides and alkylzinc reagents without an induction period, even at low temperatures (0,°C or ,20,°C). To evaluate the influence of the catalyst structure upon the induction period, complex 9 was prepared, in which the nBu groups of 1 were displaced by more bulky 1,3,5-trimethylphenyl groups. Trimer 10 was isolated from the reaction of complex 9 and basic organometallic reagents such as CyZnCl or CyMgCl (Cy: cyclohexyl); this is consistent with the result obtained with complex 1. The rate in the induction period of the model reaction catalyzed by 9 was faster than that with 1. Plausible catalytic cycles for the reaction, based upon the experimental results, are discussed. [source]

Behaviour of [PdH(dppe)2]X (X=CF3SO3,, SbF6,, BF4,) as Proton or Hydride Donor: Relevance to Catalysis

CHEMISTRY - A EUROPEAN JOURNAL, Issue 15 2004
Michele Aresta Prof.
Abstract The synthesis, characterization and properties of [PdH(dppe)2]+CF3SO3,,0.125,THF (1; dppe=1,2-bis(diphenylphosphanyl)ethane) and its SbF6, (1,) and BF4, (1,,) analogues, the missing members of the [MH(dppe)2]+X, (M=Ni, Pd, Pt) family, are described. The Pd hydrides are not stable in solution and can react as proton or hydride donors with formation of dihydrogen, [Pd(dppe)2]2+ and [Pd(dppe)2]. Complexes 1,1,, react with carbocations and carbanions by transferring a hydride and a proton, respectively. Such H, or H+ transfer occurs also towards unsaturated compounds, for example, hydrogenation of a CC double bond. Accordingly, 1 can hydrogenate methyl acrylate to methyl propionate. Complex 1,, is an effective (hourly turnover frequency=16) and very selective (100,%) catalyst for the hydrogenation of cyclohexen-2-one to cyclohexanone with dihydrogen under mild conditions. Density functional calculations coupled with a dielectric continuum model were carried out to compute the energetics of the hydride/proton transfer reactions, which were used to rationalize some of the experimental findings. Theory provides strong support for the thermodynamic and kinetic viability of a tetracoordinate Pd complex as an intermediate in the reactions. [source]

Structure, DNA Binding Studies and Cytotoxicity of Complex [Pd(phen)(L -asp)]·3H2O

CHINESE JOURNAL OF CHEMISTRY, Issue 6 2009
Enjun GAO
Abstract The palladium(II) complex of [Pd(phen)(L -asp)]·3H2O (phen=1,10-phenanthroline, H2L-asp=L -aspartic acid) has been synthesized from a solution reaction and analyzed by elemental analyses, 1H NMR and IR spectra. Moreover, the complex has been structurally characterized by single-crystal X-ray diffractometry. The cytotoxicity assay of the complex and cis -DDP as reference substance against three different cancer cell lines (Hela, Hep-G2 and KB) has been conducted. The results show that the Pd complex exhibits higher cytotoxicity against Hela system. The study on the interaction of the Pd complex with fish sperm DNA (FS-DNA) has been performed with diverse spectroscopic techniques, showing that the complex is bound to the fish sperm DNA via an intercalative mode. Gel electrophoresis assay demonstrates the ability of the complex to cleave the pBR 322 plasmid DNA. [source]

A New Approach on the Active Treatment for Electroless Copper Plating on Glass

CHINESE JOURNAL OF CHEMISTRY, Issue 1 2003
Liu Zheng-Chun
Abstract A new method is described for the electroless deposition of copper onto glass. Commercially available glass slide was modified with ,-amimopropyltrimethoxysilane to form self-assembled monolayer (SAM) on it. Then it was dipped directly into PdCl2 solution instead of the conventional SnCl2 sensitization followed by PdCl2 activation. Experimental results showed that the Pd2+ ions from PdCl2 solution were coordinated to the ammo groups on the glass surface resulting in the formation of N,Pd complex. In an electroless copper bath containing a formaldehyde reducing agent, the N,Pd complexes were reduced to Pd0 atoms, which then acted as catalysts and initiated the deposition of copper metal. Although the copper deposition rate on SAM-modified glass was slow at the beginning, it reached to that of conventional method in about 5 min. [source]

A Density Functional Theory Study of the Stille Cross-Coupling via Associative Transmetalation.

ADVANCED SYNTHESIS & CATALYSIS (PREVIOUSLY: JOURNAL FUER PRAKTISCHE CHEMIE), Issue 6 2007
Coordinating Solvents, The Role of Ligands
Abstract An associative mechanism has been computationally characterized for the Stille cross-coupling of vinyl bromide and trimethylvinylstannane catalyzed by PdL2 (L=PMe3, AsMe3) with or without dimethylformamide as coordinating ligand. All the species along the catalytic cycles that start from both the cis - and the trans -PdL(Y)(vinyl)Br complexes (Y=L or S; L=PMe3, AsMe3 or PH3; S=DMF) have been located in the gas phase and in the presence of polar solvents. Computations support the central role of species trans -PdL(DMF)(vinyl)Br which react by ligand dissociation and stannane coordination in the rate-limiting transmetalation step via a puckered four-coordinate (at palladium) transition state comprised of Pd, Br, Sn and sp2 C atoms. A donating solvent may enter the catalytic cycle assisting isomerization of cis -PdL2(vinyl)Br to trans -PdL(DMF)(vinyl)Br complexes via a pentacoordinate square pyramidal Pd intermediate. In keeping with experimental observations, the activation energies of the catalytic cycles with arsines as Pd ligands are lower than those with phosphines. Polytopal rearrangements from the three-coordinate T-shaped Pd complexes resulting from transmetalation account for the isomerization and the CC bond formation on the reductive elimination step. [source]

Cyclopolymerization and Copolymerization of Functionalized 1,6-Heptadienes Catalyzed by Pd Complexes: Mechanism and Application to Physical-Gel Formation

Comparative Experimental and EXAFS Studies in the Mizoroki,Heck Reaction with Heteroatom-Functionalised N-Heterocyclic Carbene Palladium Catalysts

CHEMISTRY - A EUROPEAN JOURNAL, Issue 13 2007
Steven G. Fiddy Dr.
Abstract A study on the Mizoroki,Heck coupling of selected aryl bromides with acrylates catalysed by a series of Pd complexes of bidentate pyridyl-, picolyl-, diphenylphosphinoethyl- and diphenylphosphinomethyl-functionalised N-heterocyclic carbene (NHC) is reported. The observed activity is dependent on the type of solvent and base used and the nature of the "classical" donors of the mixed-donor bidentate ligand and its bite angle. A mechanistic model is presented for the pyridine-functionalised NHC complexes based on an in situ EXAFS study under dilute catalyst conditions (2,mM Pd). The model involves pre-dissociation of the pyridine functionality and oxidative addition of ArBr in the early stages of the reaction, as well as formation of monomeric and dimeric Pd species at the time of substrate conversion. [source]