Palladium extraction by amines from nitrate medium in the presence of chloride ions

The extraction of palladium has been studied in amine-solvent-HNO₃–HCl systems. It has been found that palladium is extracted in the forms Am₂PdCl₄ and Am₂Pd₂Cl₆ simultaneously /Am=ammonium cation/.     

Interaction of Pd(II) with Glutamic Acid

Pd(II) complexes with glutamic acid of the composition K[Pd(HGlu)Cl₂] (I) and [Pd(HGlu)₂] (II) were synthesized and studied by IR and electronic absorption spectroscopy methods. Pd²⁺–H₂O–Cl^– and Pd²⁺–H₂O–Cl^––H₂Glu systems were analyzed by pH-metric titration. The most essential Pd(II) complex forms were established by mathematical modeling and their formation constants were calculated. The electronic absorption spectra of complexes I and II were measured in aqueous and physiological solutions. Complex I was found to be biologically active and to exhibit antimetastatic properties.     

X-ray photoelectron and quantum-chemical investigation of the electronic structure of palladium chloride

The results of an x-ray photoelectron investigation of the core levels and valence band of PdCl₂ have been presented. A theoretical interpretation has been formulated on the basis of calculations of the expanded Pd₆Cl₈ ⁴⁺ and Pd₆Cl₁₂ clusters by the X-scattered wave method and a band calculation of a one-dimensional [PdCl₂]_n crystal. The proposed scheme for the electronic structure of PdCl₂ satisfactorily accounts for the features of the x-ray photoelectron spectra, including the presence of satellite lines due to many-electron excitation. The inadequacy of the single-sphere approximation in the framework of the model of PdCl₄ ^2– for the theoretical interpretation of the electronic structure has been noted, and the significant role of the covalent component of the Pd-Cl bonds in the formation of palladium chloride has been demonstrated. The results of the XPS investigation in conjunction with the quantum-chemical calculations makes it possible to examine the optical spectra and the x-ray absorption and emission spectra of PdCl₂ on a single basis.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 4, pp. 409–418, July–August, 1986.     

Formation and Properties of Hydrogenation Catalysts Based on Palladium Complexes with Primary Phosphines

The formation and catalytic properties of hydrogenation catalysts based on palladium(II) complexes with primary phosphines were studied. With the use of IR and UV spectroscopy, XRD analysis and GLC, it was found that the interaction of bis(acetylacetonato)palladium(II) or palladium(II) acetate with primary phosphines in an inert atmosphere resulted in the formation of polynuclear palladium complex associates mainly containing μ³-PR and a coordinated phosphine. Polynuclear palladium complexes and the palladium phosphide Pd₆P, which is formed from these complexes in an atmosphere of hydrogen, serve as supports for Pd(0) clusters. The effects of the ratio between initial components and the nature of the acido ligand at the palladium atom on the optimum conditions of catalyst formation were considered.__________Translated from Kinetika i Kataliz, Vol. 46, No. 4, 2005, pp. 609–614.Original Russian Text Copyright © 2005 by Belykh, Goremyka, Gusarova, Sukhov, Shmidt.     

Palladium π-adduct of corannulene

The ternary palladium π-adduct of corannulene and benzene, [Pd₆Cl₁₂·(C₂₀H₁₀)₂·(C₆H₆)₂]·C₆H₆ (1), has been prepared by reacting the cubic Pd₆Cl₁₂-cluster with C₂₀H₁₀ in benzene. It was structurally characterized to reveal η¹-binding of Pd₆Cl₁₂ to a hub C-atom of the convex surface of corannulene (Pd?C, 3.085(3) Å) and its η⁶-complexation to benzene (Pd?C_centroid, 3.431(3) Å). The behavior and persistence of 1 in some aromatic solvents has been revealed by UV-vis and ¹H NMR spectroscopy studies.     

Palladium(II)-catalysed H/D allylic exchange in alkenes: An intermediacy of palladium(IV)?

Evidence is presented that the dimeric π-allylic species [(η³-allyl)PdCl]₂ is not intermediate in the Li₂Pd₂Cl₆-catalysed allylic H/D exchange in alkenes. Neither H/D exchange in α-methylstyrene, nor enrichment of [(η³-2-PhC₃H₄)PdCl]₂, was observed when the latter complex was incubated at 100°C in D₃CCOOD either in the presence or in the absence of PhC(CH₃)?CH₂, respectively. The kinetics of H/D exchange in α-methylstyrene catalysed by Li₂Pd₂Cl₆ were studied in some detail. The exchange proceeds at highest rates when reduction of palladium(II) takes place and is much slower in the presence of 1,4-benzoquinone as a palladium reoxidant. The exchange rate is directly proportional to the alkene and catalyst concentrations and independent of the reoxidant concentration. It is suggested that the palladium(II)-catalysed exchange involves an intermediate hydrid-allyl species where palladium has a formal oxidation state of IV.     

1, 2-Dithiolium salts

4-(p-Tolyl)-1,2-dithiolium hydrogen sulfate (I) is not a specific analytical reagent for the majority of anions, and it is not very selective, only in a few cases attaining pD=5 (MoO₄ ^2–, [Hg(CNS)₄]^2–, and [PtCl₆]^2–). All strongly colored anions give colored salts with I. Among the weakly colored anions, the [Fe(CN)₆]^4– anion is worthy of special note, since it forms a deeply colored salt with I. This anion can be detected with I in the presence of Cl^–, Br^–, I^–, CNS^–, ClO₄ ^–, IO₄ ^–, and ReO₄ ^–, which form fairly readily soluble salts with I. Compound I is also a fairly selective reagent for Pd²⁺ in acid solution (pD=5).For part II, see [1].Translated from Khimiya Geterotsiklicheskikh Soedinenii, Vol. 6, No. 5, pp. 595–597, May, 1970.     

Oxidation of palladium(II) by hexacyanoferrate(III) in aqueous ethanoic acid: a mechanistic study

The oxidation of Pd^II by Fe(CN) ₆ ^3– has been studied in 55% MeCO₂H–H₂O containing 4.0 mol dm^–3 HCl, the oxidation being made possible by altering redox potentials. The active species of Pd^II and Fe(CN) ₆ ^3– are PdCl ₃ ^– and H₂Fe(CN) ₆ ^– , respectively. A possible mechanism is proposed and verified, and the reaction constants involved have been evaluated.     

Complexes with N,S donor ligands. Nickel(II), copper(II), cobalt(II), iron(III) and palladium(II) complexes of biacetylbis(mercaptophenylimine) and their reactions with alkyl and aryl halides,leading to the formation of macrocycles

Summary Compounds of the type ML, where M is a divalent metal ion such as Ni, Cu and Co and H₂L=biacetylbis(mercaptophenylimine) and [MLCl], where M is iron(III) have been prepared and characterised by elemental analysis, molar conductances, magnetic susceptibilities and i.r. and electronic spectral data.A trinuclear complex of palladium(II), [Pd₃L₂]Cl₂, has also been isolated and characterised.¹H.n.m.r. spectroscopic data, along with other physico-chemical analytical results, support this trinuclear formulation.Reactions of these complexes, except for the palladium(II) complex, with difunctional alkylating agents produce macrocyclic derivatives with alkylation of the coordinated mercaptide groups.     

Palladium(II) Complexes of 1-vinylimidazole

Two new co-ordination compounds of Pd^II with 1-vinylimidazole of the formulae [PdL₄]Cl₂·3H₂O and trans-[PdL₂Cl₂], where L is a 1-vinylimidazole molecule, have been obtained. The compounds were characterised by spectroscopic, molar conductivity, thermogravimetric and magnetochemical measurements. Single crystal X-ray structure analyses of the complexes were also carried out. The compounds are diamagnetic with square-planar coordinatination around the palladium(II) ions. Other physico-chemical properties of the both complexes are compatible with their structures.     

Ma?analyse und Katalyse

Zusammenfassung Die Anwendung der thermometrischen Methode auf die katalytische Endpunktsindikation bei fällungsmaßanalytischen Bestimmungen wird diskutiert. Die direkte Titration von Silber, Quecksilber(II) und Palladium(II) sowie die Bestimmung mehrerer Anionen (Cl^–, Br^–, J^–, SCN^–, CN^–, [Fe(CN)₆]^4– und S^2–) durch Rücktitration mit Jodidmaßlösung wird beschrieben. Die bekannte jodidkatalysierte Reaktion zwischen Cer(IV) und Arsen(III) dient als Indicator. Die oben genannten Ionen können auf diese Weise im Mikrogrammbereich mit befriedigender Genauigkeit bestimmt werden.

---

Volumetric analysis and catalysisIV. Determinations by precipitation titration with potassium iodide and thermometric end-point indication

The application of the therinometric method to the catalytic endpoint indication in volumetric determinations by precipitation reactions is discussed. The direct titration of silver, mercury(II) and palladium(II) as well as the determination of several anions (Cl^–, Br^–, J^–, SCN^–, CN^–, [Fe(CN)₆]^4– and S^2–) by backtitration with iodide standard solution is described. The well known reaction between cerium(IV) and arsenic(III), catalysed by iodide, serves as an indicator. The ions mentioned can thus be determined in the microgram range with good accuracy.

---

---

III. Mitteilung: Weisz, H., u. D. Klockow: diese Z. 232, 321 (1967).

---

Wir danken der Alexander von Humboldt-Stiftung sowie der Deutschen Forschungsgemeinschaft, die diese Arbeit durch ein Dozentenstipendium (T. K.) bzw. ein Habilitandenstipendium (D. K.) ermöglicht haben. - Herrn cand.-chem. E. Schröter sind wir für seine Hilfe beim Aufbau der Meßanordnung zu Dank verpflichtet.     

P NMR study of the stoichiometry, stability and thermodynamics of complex formation between palladium(II) acetate and bis(diphenylphosphino)ferrocene

The complexation reaction between palladium (II) acetate, and 1,1′-bis(diphenylphosphino)ferrocene, DPPF, was investigated in two different deuterated solvents CDCl₃ and DMSO at various temperatures using ³¹P NMR spectroscopy. The exchange between free and complexed DPPF is slow on the NMR time scale and consequently, two ³¹P NMR signals were observed. At metal ion-to-ligand mole ratio larger than 1, only one ³¹P NMR signal was observed, indicating the formation of a 1:1 Pd²⁺–DPPF complex in solution. The formation constant of the resulting 1:1 complexes was determined from the integration of two ³¹P signals. The values of the thermodynamic parameters (ΔH, ΔS and ΔG₂₉₈) for complexation were determined from the temperature dependence of stability constants. It was found that, in both solvents, the resulting complex is mainly entirely enthalpy stabilized and the ΔH compensates the TΔS contribution.     

New pentafluorothiophenoxo derivatives of tin,lead, antimony,bismuth, gold and platinum

Summary Salts of the anions [SnX₅]^–, [SnX₄Cl, [SnX₃Cl₂]^–, [SnX₃]^–, [PbX₃]^–, [SbX₄]^–, [SbX₃Cl]^–, [SbX₂Cl₂]^–, [BiX₄]^–, [AuCl₂]^–, [AuX₂]^–, [AuXCl]^–, [AuX₄]^–, [Au₂X₆]^2– and [PtX₄]^2–, where X^– = C₆F₅S^–, have been isolated and characterised. The neutral SbX₃ and BiX₃ species, have also been isolated and shown to be pyramidal monomers (¹⁹F.n.m.r., i.r., and Raman spectral evidence). Various physical properties of the complexes prepared, as well as their stereochemistries (where these could be ascertained), are similar to those of the known corresponding halogeno compounds of these elements. These results further demonstrate the pseudo-halide nature of the pentafluorothiophenoxide ion.Author to whom all correspondence should be directed at: Laboratoire de Chimie de Coordination, Uniyersité Louis Pasteur, 67008 Strasbourg, France.     

Preparation,characterization and antifungal properties of nickel(II) complexes of tridentate ONS ligands derived from N-methyl-S-methyldithiocarbazate and the X-ray crystal structure of the [Ni(ONMeS)CN]·H2O complex

Nickel(II) complexes of general empirical formula, NiLX·nH₂O (L = deprotonated form of the Schiff base formed by condensation of N-methyl-S-methyldithiocarbazate with 2-hydroxybenzaldehyde or 5-bromo-2-hydroxybenzaldehyde; X = Cl^–, Br^–, NCS^–, AcO^– or CN^–; n = 0, 1) have been prepared and characterized by a variety of physico-chemical techniques. Magnetic and spectroscopic data support a square-planar structure for these complexes. The crystal structure of the [Ni(ONMeS)CN]·H₂O complex (ONMeS = anionic form of the 2-hydroxybenzaldehyde Schiff base of N-methyl-S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted square-planar structure in which the Schiff base is coordinated to the nickel(II) ion as a uninegatively charged anion coordinating via the phenolic oxygen atom, the azomethine nitrogen atom and the thione sulfur atom. The fourth coordination position is occupied by a cayano ligand. The antifungal properties of the Schiff bases and their nickel(II) complexes were studied against three plant pathogenic fungi. The ligands display moderate fungitoxicities against these organisms but their nickel(II) complexes are less active than the free ligands.     

Theoretical Study of the Metal–Metal Interaction in Dipalladium(I) Complexes

Correlated ab initio calculations have been performed on three dipalladium(I) complexes. These compounds differ both by the metal–metal interaction and by the metal–ligand interaction. The [Pd₂Cl₂(μ −H₂PCH₂PH₂)₂] complex exhibits a σ overlap between the two binding metallic orbitals and has no bridging ligand. In [Pd₂Cl₄(μ −CO)₂]²⁻, the leading interaction between the two palladium involves a π overlap between the metallic orbitals and goes through the two bridging CO ligands. In [Pd₂Cl₂(μ −CO)(μ −H₂PCH₂ PH₂)₂], a single CO ligand bridges the two palladium atoms which interact through a hybrid σ–δ overlap. The three compounds also differ by the metal–metal distances. Surprisingly enough, while the palladium atoms are formally d ⁹ in all these complexes, none of them is paramagnetic. We propose here a detailed analysis of the electronic structures of these compounds and rationalize their chemical structures as well as the role of back-donation in the CO bridged compounds. Finally, since highly correlated treatments are used to describe these complexes, a detailed study of the role of both non-dynamical and dynamical correlations is performed. Concerning the [Pd₂Cl₄(μ −CO)₂]²⁻ complex, this analysis has revealed that the complex is not bound at the lowest correlated levels of calculation and therefore dynamical correlation is alone responsible for its binding energy.     

Solvolysis of palladium(II) and platinum(II) complexes of asymmetric ligands: Synthesis and structural characterization of [Pd(AMP)(dmso)Cl]BF4 and [Pt(AMP)(dmso)Cl]ClO4

Treatment of [M(AMP)Cl₂] (M = Pt^II, Pd^II; AMP = 2-aminomethylpyridine) with 1 mole of AgX (X = ClO₄, BF₄, PF₆) in dmso yields [M(AMP)(dmso)Cl]X. Single crystal X-ray structure determinations of the Pd^II and Pt^II complexes indicate that dmso is S-bondedtrans to the pyridyl ring in both complexes. (2-Aminomethylpyridine)chloro(dimethylsulphoxide-S) palladium(II) tetrafluoroborate.     

Copper(II) and palladium(II) complexes of N,N′-bis(2-hydroxyethyl)stilbenediamine

A new 1,2-diamine ligand, N,N-bis(2-hydroxyethyl)stilbenediamine (L), has been prepared by reduction of the condensation product of benzaldehyde with 2-aminoethanol with Al amalgam. Mononuclear complexes of the [CuL(H₂O)]X₂ type where X=Cl^– or AcO^– with Cu^II and PdLCl₂ with palladium(II) have been prepared and characterized by elemental analysis and i.r., u.v.–vis. or ¹H-n.m.r. spectroscopy.     

Metal ion complexes of 2-picolinamineN-oxide

Summary A series of cobalt(II), nickel(II) and copper(II) complexes of 2-picolinamineN-oxide, HA, has been prepared. Solids of formula [M(HA)₃](BF₄)₂ (M=cobalt(II) or nickel(II); [Cu(HA)₂]X₂ (X=BF ₄ ^– , NO ₃ ^– ); [Co(HA)₂X₂] (X=Cl^– or Br^–); [Ni(HA)₂Cl₂] and [Cu(HA)X₂] (X=Cl^– or Br^–] have been isolated and characterized by partial elemental analyses, molar conductivities, magnetic susceptibilities, DSC-TGA, and spectral methods. All complexes were found to be monomeric, and their spectral parameters are compared with those of the metal ion complexes ofN-alkyl-2-picolinamineN-oxides, 2-dialkylaminopyridineN-oxides and 2-picolinamine. The cobalt(II) and nickel(II) halide complexes spectrally show a mixture of octahedral and tetrahedral centres.     

Iminophosphines: synthesis, formation of 2,3-dihydro-1H-benzo[1,3]azaphosphol-3-ium salts and N-(pyridin-2-yl)-2-diphenylphosphinoylaniline, coordination chemistry and applications in platinum group catalyzed Suzuki coupling reactions and hydrosilylations

The aprotic and protic bi- and multidentate iminophosphines 2-Ph₂PC₆H₄N=CR¹R² (R¹=H, R²=Ph=2a; R¹=Me R²=Ph=2b; R¹=H, R²=2-thienyl=2c; R¹=H, R²=C₆H₄-2-PPh₂=2d; R¹=H, R²=C₆H₄-2-OH=2e, R¹=H, R²=C₆H₄-2-OH-3-Bu^t=2f; R¹=H, R²=CH₂C(O)Me=2g) have been prepared by the acid catalyzed condensation of 2-(diphenylphosphino)aniline with the corresponding aldehyde–ketone. Iminophosphine 2d can be reduced with sodium cyanoborohydride to give the corresponding amino-diphosphine 2-Ph₂PC₆H₄N(H)CH₂C₆H₄-2-PPh₂ (2h). In the presence of a stoichiometric quantity of acid, 2-(diphenylphosphino)aniline reacts in an unexpected manner with benzaldehyde, salicylaldehyde, or acetophenone to give the corresponding 2,3-dihydro-1H-benzo[1,3]azaphosphol-3-ium salts and with pyridine-2-carboxaldehyde to give N-(pyridin-2-ylmethyl)-2-diphenylphosphinoylaniline, the latter of which has been characterized by single-crystal X-ray crystallography, as its palladium dichloride derivative. The attempted condensation of 2-(diphenylphosphino)aniline with pyridine-2-carboxaldehyde to give the corresponding pyridine-functionalized iminophosphine resulted in an unusual transformation involving the diastereoselective addition of two equivalents of aldehyde to give 1,2-dipyridin-2-yl-2-(o-diphenylphosphinoyl)phenylamino-ethanol, which has been characterized by a single-crystal X-ray structure determination. The bidentate iminophosphine 2-Ph₂PC₆H₄N=C(H)Ph reacts with [(cycloocta-1,5-diene)PdClX] X=Cl, Me) to give [Pd{2-Ph₂PC₆H₄N=C(H)Ph}ClX] and the imino-diphosphine 2-Ph₂PC₆H₄N=C(H)C₆H₄-PPh₂ reacts with [(cycloocta-1,5-diene)PdClMe] to give [Pd{2-Ph₂PC₆H₄N=C(H)C₆H₄---PPh₂}ClMe] and each has been characterized by single-crystal X-ray crystallography. The monobasic iminophosphine 2-Ph₂PC₆H₄N=C(Me)CH₂C(O)Me reacts with [Ni(PPh₃)₂Cl₂] in the presence of NaH to give the phosphino–ketoiminate complex [Ni{2-Ph₂PC₆H₄N=C(Me)CHC(O)Me}Cl], which has been structurally characterized. Mixtures of iminophosphines 2a–h and a palladium source catalyze the Suzuki cross coupling of 4-bromoacetophenone with phenyl boronic acid. The efficiency of these catalysts show a marked dependence on the palladium source, catalysts formed from [Pd₂(OAc)₆] giving consistently higher conversions than those formed from [Pd₂(dba)₃] and [PdCl₂(MeCN)₂]. Catalysts formed from neutral bi- and terdentate iminophosphines 2a–d gave significantly higher conversions than those formed from their monobasic counterparts 2e–f. Notably, under our conditions the conversions obtained with 2a–c compare favorably with those of the standards; catalysts formed from tris(2-tolyl)phosphine and tris(2,4-di-tert-butylphenyl)phosphite and a source of palladium. In addition, mixtures of [Ir(COD)Cl]₂ and 2a–h are active for the hydrosilylation of acetophenone; in this case catalysts formed from monobasic iminophosphines 2e–f giving the highest conversions.     

Spectrophotometric determination of palladium(II) with phenylfluorone in the presence of hexadecylpyridinium bromide

Phenylfluorone reacts with palladium(II) in the presence of hexadecylpyridinium bromide to form a water-soluble chelate with an absorption maximum at 630 nm, the absorbance being constant in the pH-range of 9.0–10.2. At this wavelength Beer's law is obeyed up to 7.25 × 10^–5 mol/L palladium(II). The sensitivity is very high and the molar absorptivity is 8.5 × 10⁴ L mol^–1 cm^–1, permitting the determination of palladium(II) at µg level. The ratio of palladium to phenylfluorone in the complex is 1:1. The method has successfully been applied to the determination of palladium in titanium alloys.