Palladium Chloride Complexes Research Articles

Stereoselectivity of Acetylene Hydrochlorination over Supported PdCl<sub>2</sub>/С Catalysts

The products of catalytic hydrochlorination of acetylene-D2 over palladium chloride complexes supported on activated carbon are a mixture of vinyl chloride stereoisomers resulting from syn- and anti-addition of the hydrogen chloride molecule to the triple bond. The reaction is accompanied by isomerization of primary trans-vinyl chloride into its cis-stereoisomer, but the characteristic isomerization times exceed significantly the duration of acetylene hydrochlorination. This fact allowed us to estimate the portion of products formed exclusively during the catalytic reaction, the difference in the effective activation energies of the syn- and anti-addition routes (~21 kJ/mol), and to demonstrate a monotonic increase in the part of the syn-addition product with increasing mass loading ω of the active metal, reaching saturation at ω 2 wt %.

Palladium complexes bearing aromatic Bis-aldimine N^N^N pincer ligands; activity as catalysts in the hydrogenation of carbon dioxide

CO2 hydrogenation can serve as an avenue for the use of CO2 as a C1 carbon source whiles simultaneously serving as a means of hydrogen ‘storage’. Herein we report on the synthesis of new pyridine-2,6-bis(methanylylidene)bis(CH = NR)- palladium chloridecomplexes were(R = Ph, p-Br-C6H4, 2,6-dimethyl-C6H3). All the complexes were fully characterized by 1H NMR, 13C NMR, FT-IR, elemental analysis, mass spectrometry and single-crystal X-ray diffraction studies where appropriate. This work sought to investigate and discuss the role of substituents in respect of electronic effects, choice of pincer ligand system backbone, and steric effects of the substituents and the role it has on the hydrogenation of CO2. These pincer complexes were investigated as catalysts in the hydrogenation of CO2 and were found to be efficient in the direct catalytic carbon dioxide hydrogenation to formate with the highest TON at 520.

Electrochemical Grafting of an Aminated Poly(methyl methacrylate) (PMMA)-like Liner onto a Silicon Surface for the Metallization of Microfeatures

The micro/nanofabrication industry’s transition from physically deposited dielectric films toward relatively inexpensive insulating polymeric materials faces a challenging metallization step in progression. In this work, we demonstrate a metallization scheme constituting simple and completely aqueous chemical steps─from Si passivation to metallization. We first propose a versatile diazonium-based electrochemical process to graft an in situ aminated poly(methyl methacrylate) (PMMA) liner onto Si microfeatures with high step-coverage. These amine-terminated groups functionalize the grafted PMMA-like liner with palladium chloride complex activators and allow direct autocatalytic deposition of Ni–B film while avoiding any further amination step as conventionally required for polymeric surfaces. The obtained Ni–B film exhibiting high uniformity, strong adhesion to the polymer film, and excellent step-coverage from the top, sidewall, and bottom of the microstructures fulfills all requirements of a conducting seed layer for the subsequent electrolytic deposition of copper.

Palladium(Ii) Chloride Complex Ion Recovery from Aqueous Solutions Using Adsorption Process on Chemically Oxidized Activated Carbons

Palladium(Ii) Chloride Complex Ion Recovery from Aqueous Solutions Using Adsorption Process on Chemically Oxidized Activated Carbons

1,2,3-Triazole lamellar liquid crystal and its non-covalent palladium complex dimer: structure, mesomorphism and self-assembly properties

ABSTRACT 1,4-disubstituted 1H-1,2,3-triazoles L was successfully synthesised using a catalyst-free click reaction between an internal alkyne and an azide compound. Refluxing click product L and palladium chloride in a homogeneous mixed solvent led to the formation of the non-covalent palladium chloride complex PdCl2-L2 , which was characterised by X-ray crystallographic analysis of the template compound, indicating that the complex adopts predominant trans-trans isomeric orientations. The two compounds showed a typical fan-shaped texture of the lamellar mesophase. Because of weak Pd-N coordination bond connections, PdCl2-L2 is a monotropic liquid crystal with a narrower mesomorphic temperature range and relatively poorer thermal stability than ligand L. Furthermore, both L and the complex dimer can self-assemble into strip-shaped nanostructures on the oriented graphite substrate surface.

Green Procedure for Aerobic Oxidation of Benzylic Alcohols with Palladium Supported on Iota-Carrageenan in Ethanol.

The search for selective heterogeneous catalysts for the aerobic oxidation of alcohols to ketones and aldehydes has drawn much attention in the last decade. To that end, different palladium-based catalysts have been proposed that use various organic and inorganic supports. In addition, supports that originate from a biological and renewable source that is also nontoxic and biodegradable were found to be superior. We heterogenized palladium chloride or acetate complexes with triphenylphosphine trisulfonate on iota-carrageenan xerogel by simple mixing of the complex and the polysaccharide in water. The resulting polysaccharide-catalyst mixture then underwent deep freeze and lyophilization, after which the catalyst was characterized by TEM, XPS and SEM-EDS and tested in aerobic oxidation. The new heterogeneous catalysts were successfully used for the first time in the aerobic oxidation of benzylic alcohols. Moreover, they were easily removed from the reaction mixture and recycled, yielding an increase in activity with each subsequent reuse. As determined by TEM and XPS, the reduction in palladium and the formation of nanoparticles during the reaction in ethanol yielded more active species and, therefore, higher conversion rates. A SEM-EDS analysis indicated that the palladium was thoroughly dispersed in the xerogel catalysts. Moreover, the xerogel catalyst was observed to undergo a structural change during the reaction. To conclude, the new heterogeneous catalyst was prepared by a simple and straightforward method that used a non-toxic, renewable and biodegradable support to yield an active, selective and recyclable heterogeneous system.

Oxidation of Olefins to Carbonyl Compounds: Modern View of the Classical Reaction

The results of 60 years' research into the mechanisms of olefin oxidation catalyzed by palladium complexes (Wacker oxidation) are analyzed. The concepts of the mechanisms of related oxidative carboxylations (Moiseev reaction) and alkoxylations are discussed. This review considers the regularities of processes in aqueous organic solvents; the problems of regio- and stereoselectivity of reactions; and the role of co-catalysts, oxidants, and ligands, including asymmetric catalysis. The effect of transition from anionic (or neutral) to cationic palladium chloride complexes in water or aqueous organic media on the mechanism of olefin oxidation is discussed in detail.

Complexes of palladium(II) chloride with 3-(pyrazol-1-yl)propanamide (PPA) and related ligands

Four new derivatives of the versatile polyfunctional ligands 3-(pyrazol-1-yl)propanamide (1, = PPA) and 3-(3,5-dimethylpyrazol-1-yl)-propanamide (2, = Me2PPA) have been prepared, in which one of the amide hydrogens on 1 and 2 is formally replaced by alkyl residues. X-Ray diffraction studies revealed that, in contrast to 1 and 2, the N-isopropyl substituted derivatives 3 and 4 form supramolecular hydrogen-bonded chains rather than two-dimensional arrays, and the N-(2-methyl-4-oxypentan-2-yl) (=MOP) substituted compounds 5 and 6 exist as cyclic dimers in the solid state. Reactions of PdCl2(COD) (COD = 1,5-cyclooctadiene) with 2 equiv. of the corresponding ligands 1–6 in all cases afforded trans-PdCl2(L)2 complexes (7–12). X-ray crystal structure determinations of 8, and 10–12 revealed κN-monodentate coordination of the PPA-type ligands.

Synthesis, solution behaviour and potential anticancer activity of new trinuclear organometallic palladium(II) complex of {S}-1-phenylethyl dithiooxamide: Comparison with the trinuclear heterobimetallic platinum(II) analogue

Addition of H2R2DTO (R = {S}-1-phenylethyl and DTO = dithiooxamide) to the bis(benzonitrile)palladium(II) chloride complex in chloroform afforded the mononuclear Pd(DTO)2·2HCl complex. The complex treated with NaHCO3 for removing of HCl and then reacted with [Pd(ƞ3-allyl)(µ-Cl)]2 for preparation of a new trimetallic organopalladium(II) complex. The molecular structure of the trimetallic complex was determined by X-ray diffraction indicating a planar geometry around each palladium center. Also, variable temperature spectroscopy for this complex was performed in CDCl3 in the range 298–390 K, and simulations of the dynamic spectra were performed using the gNMR program. A comparison between the target-based activity of the Pd(II) complex and its trinuclear heterobimetallic platinum(II) analogue as potential anticancer agents was also conducted. All the biological tests showed that both Pd(II) and Pt(II) complexes can fairly inhibit cathepsin B (Cat-B) and cathepsin L (Cat-L) as well as two out of three activities of 20S proteasome.

Palladium‐Catalyzed C–C Ring Closure in α‐Chloromethylimines: Synthesis of 1H‐Indoles

The C‐C ring closure of α‐chloromethyl alkyl or aryl N‐aryl imines catalyzed with 1 to 10 % Pd(OAc)2/P(p‐tolyl)3 afford efficiently 2‐aryl‐ and 2‐alkyl‐1H‐indoles. The heterocyclization reaction involves the initial formation of [2‐(arylimino)ethyl]palladium(II) chloride complexes with subsequent C‐H activation of the aromatic amine ring. Readily or commercially available α‐chloromethyl‐aryl or ‐alkyl ketones are used as the precursors. Functionalized indoles at the benzene ring are obtained when the imines are derived from substituted anilines.

Ion-Exchange Sorption of Palladium(II) from Hydrochloric Acid Solutions in the Presence of Silver(I)

The sorptive extraction of palladium(II) chloride complexes in the presence of silver(I) chloride complexes from 2 and 4 M aqueous solutions of HCl with a series of Purolite anionites with different functional groups is studied. An anion exchange mechanism of sorption is identified from Raman spectroscopy data. Kinetic properties that are inherent to the investigated ionites and allow the elution of palladium(II) and silver(I) after their extraction in a dynamic mode are revealed.

Palladium and Platinum 2,4-cis-amino Azetidine and Related Complexes.

Seven N,N'-palladium(II) chloride complexes, one N,N'-palladium(II) acetate complex of 2,4-cis-azetidines where prepared and analyzed by single crystal XRD. Two platinum(II) chloride N,N'-complexes of 2,4-cis-azetidines where prepared and analyzed by single crystal XRD. Computational analysis and determination of the %Vbur was examined conducted. A CNN' metallocyclic complex was prepared by oxidative addition of palladium(0) to an ortho bromo 2,4-cis-disubstituted azetidine and its crystal structure displays a slightly pyramidalized metal-ligand orientation.

Palladium(II) Chloride Complex Ion Recovery from Aqueous Solutions Using Adsorption on Activated Carbon

The process of palladium(II) chloride complex ion adsorption on activated carbon was investigated. The influence of variable parameters such as the initial concentration of the Pd(II) complex (from 0.04 to 2.25 mmol·kg–1) and temperature (from 294 to 348 K) was determined. Experiments were conducted in the solution with pH equal to 0 and 1. It was found that the Freundlich adsorption isotherm describes the process better than the Langmuir model. The observed sorption capacity as high as q294K = 42.4 mg·g–1 and q323K = 67 mg·g–1 for activated carbon was found at 294 and 323 K, and it is increasing with temperature increase. The obtained results showed that the palladium(II) complex may react with functional groups present on the surface of activated carbon. The thermodynamic parameters such as the equilibrium constant and heat and entropy of adsorption were derived. The enthalpy value is equal to −6.7 kJ·mol–1, and the entropy is equal to −23 J·mol–1·K–1. It is suggested that, during chemisorption of palla...

Influence of the Degree of Chitosan Sulfoethylation on the Sorption of Palladium(II) Chloride Complexes from Multicomponent Solutions

The influence exerted by the degree of substitution of sulfoethylated chitosan cross-linked with glutaraldehyde on the sorption of Pd(II) chloride complexes from multicomponent solutions containing Pt(IV), Cu(II), Ni(II), Co(II), Cd(II), and Zn(II) was studied. The sorption of transition metal ions under the conditions of the experiment at pH 0.5–5.0 is virtually fully suppressed. The strongest interfering effect on the Pd(II) sorption is exerted by Pt(IV). Calculation of the selectivity coefficients KPd/Pt shows that the selectivity of the Pd(II) sorption relative to Pt(IV) increases with an increase in the degree of substitution of chitosan from 0.3 to 0.5. Integral kinetic curves of the Pd(II) sorption were obtained, and the dependences were subjected to mathematical processing using the models of diffusion and chemical kinetics. The equilibrium in the palladium(II) chloride solution–sorbent system is attained within 40 min. Pd and Pt are quantitatively desorbed from the sorbent surface under dynamic conditions with 3.5 M HCl solution.

CATALYSTS OF OXIDATION REACTION OF BUTENE-1 TO METHYLETHYLKETONE

The available and simple metal complex systems of catalytic oxidation of unsaturated hydrocarbons were developed. It is shown that these systems catalyze the selective liquid-phase oxidation of butene-1 to methyl ethyl ketone by molecular oxygen at low temperature. The best results were revealed using Cu(I)Cl monovalent chloride. The catalyst for the production of methylethylketone is a binary system containing complexes of copper and palladium chloride at a molar ratio of 2:1. Hexamethylphosphoramide is used as the ligand and palladium chloride complex as an additional complex contains benzonitrile. A combined catalyst has been offered. It allows to carry out the oxidation reaction of butene to methyl ethyl ketone under mild conditions (low temperature, atmospheric pressure) with high selectivity and yield of the desired product. The proposed binary system is able to coordinate molecular oxygen and butene-1, and thus it becomes possible to conduct the oxidation reaction not directly between butene-1 and O2, and using a specific complex catalyst system allowing them to react with each other in an activated coordinated state. Absorption properties of catalysts synthesized on the bases of transition metals have been studied and activation of molecular oxygen and butane-1 has been determined. As a result of interaction of coordinated oxygen and butane-1 it is possible to carry out oxidation reaction to methylethylketone in mild condition. The specific feature of the offered binary catalyst is irreversible absorption of molecular oxygen. Mild conditions of the reaction proceeding decreases considerably amount of by-products and simplify obtaining and separation of the main product-methylethylketone. Due to the fact that the absorption of O2 is irreversible and it is possible to easily remove the excess amount of O2 after the formation of the oxygen complex. The developed method has the advantage from the point of view of safety.Forcitation:Agaguseynova M.M., Amanullayeva G.I., Bayramova Z.E. Catalysts of oxidation reaction of butene-1 to methylethylketone. Izv. Vyssh. Uchebn. Zaved. Khim. Khim. Tekhnol. 2018. V. 61. N 2. P. 53-57

Low-temperature equilibriums in solutions of isocyanide-phosphine complexes of palladium(II) chloride

cis-[PdCl2(CNR)(PPh3)] [R = Cy, t-Bu, C(Me)2CH2C(Me)3] have been synthesized via the interaction of [(PPh3)ClPd(μ-Cl)2PdCl(PPh3)] with isocyanide in CH2Cl2 at room temperature with 90–98% yield and characterized by means of mass spectrometry as well as 1H, 13C{1H, 31P}, and 31P{1H} NMR spectroscopy. The complexes structure in the solid phase has been elucidated by means of X-ray diffraction analysis. Dynamic processes in the solutions of the complexes in CDCl3 and CD2Cl2 at temperature of–95 to 60°С have been studied by means of 1H and 31P NMR spectroscopy. It has been found that the studied compounds existed exclusively in the cis-[PdCl2(CNR)(PPh3)] form in the solutions. In the case of cis-[PdCl2(CNCy)(PPh3)] in CH2Cl2, the conformational transitions of the equilibrium forms (the transition of the substituent in the cyclohexyl cycle between the equatorial and axial positions) are slowed down, the equatorial conformer prevailing in the solution (2: 1 at–95°С). Quantum-chemical simulation (DFT) has revealed that the standard Gibbs energy of the conformational transition from the axial form of cis-[PdCl2(CNCy)(PPh3)] into the equatorial one in the CH2Cl2 solution at 178 K equals–2.5 kJ/mol, being in agreement with the experimental data.

The Mechanism of Redox Reaction between Palladium(II) Complex Ions and Potassium Formate in Acidic Aqueous Solution

AbstractThe kinetics studies of redox reaction between palladium(II) chloride complex ions and potassium formate in acidic aqueous solutions was investigated. It was shown, that the reduction reaction of Pd(II) is selective in respect to Pd(II) complex structure. The kinetic of the process was monitored spectrophotometrically. The influence of chloride ions concentration, Pd(II) initial concentration, reductant concentration, ionic strength as well as the temperature were investigated in respect to the process dynamics. Arrhenius equation parameters were determined and are equal to 65.8 kJ/mol, and A = 1.12×1011s−1.

A detailed spectrophotometric investigation of the complexation of palladium(II) with chloride and bromide

As the speciation of metal species, especially the noble metals, are crucial for recovery and separation purposes, the complex formation of Pd(II), with chloride and bromide respectively, has been investigated employing spectrophotometry at 25°C and an ionic strength of 1.0M Hyperquad Simulation and Speciation (HySS) was employed to determine the ideal titration conditions and an autotitrator (equipped with a flow-through cell) was used to accurately vary the chloride and bromide concentrations over an increased number of intervals, i.e. 128 and 300 respectively. All of these data points were used to calculate the formation constants of both palladium systems employing HypSpec (software specifically developed for the determination of equilibrium constants from spectrophotometric data). The formation constants, βn, for the palladium(II)-chloride and -bromide complexes, have been determined. For [PdCln(H2O)4−n]2−n (n=0–4), the log β values are: log β1=4.49, log β2=7.80, log β3=10.18 and log β4=11.54, while the log β values for [PdBrn(H2O)4−n]2−n (n=0–4), are: log β1=5.04, log β2=9.12, log β3=12.38 and log β4=14.55. The formation constants for the palladium-chloride complexes agree well with the published data, while the formation constants for the bromide complexes differ from somewhat from published data suggesting a different, but more accurate speciation. Molar absorption spectra for all the complexes in question have been obtained. Pourbaix diagrams were constructed from the new speciation data showing the predominant species for each system.

Highly Efficient Bulky α‐Diimine Palladium Complexes for Suzuki‐Miyaura Cross‐Coupling Reaction

AbstractA series of bulky 9,10‐dihydro‐9,10‐ethanoanthracene‐11,12‐diimine methyl palladium chloride complexes (C1—C6) with different steric and electronic substituent have been applied in Suzuki‐Miyaura cross‐coupling reactions. The influence of these substituents was investigated by comparing the catalytic performance of the complexes in the cross‐coupling reactions and it can be found that the complex with bulky and electron‐donating substituent is facilitated for the cross‐coupling reaction of aryl halides with arylboronic acids under ambient atmosphere. The most active complex shows a wide substrate scope in excellent yields using very low catalyst concentration of 0.01 mol%.

On the performance of Pd and Rh catalysts over different supports in the hydrodechlorination of the MCPA herbicide

Commercial and own-made Pd and Rh catalysts supported on alumina, zeolite Y (ZY) and two kinds of silica (Fumed Silica (FS) and SBA-15), were tested in the aqueous phase hydrodechlorination of the 4-chloro-2-methylphenoxyacetic acid (MCPA) herbicide. Pd catalysts showed higher activity than Rh and regarding the supports, the following sequence was found: Al2O3>FS>ZY>>SBA-15. The catalysts with metal particle sizes within the range of 3.1–3.7nm, associated with Mn+/M° ratios between 0.7 and 1.7, showed higher activities. The most active catalysts of each series, the Al2O3-supported ones, showed a distribution of the metallic phase approaching an egg-shell configuration opposite to the rest. The Pd/Al2O3 catalyst, which was the most active, suffered a significant loss of activity upon the early stages on stream that could be ascribed to the formation of palladium chloride complexes as well as to deposition of species involved in the reaction.