Preparation of Palladium(II) and Platinum(II) Phosphine Complexes Promoted by Phase-Transfer Catalysts

The synthesis of M(PR₃)₂Cl₂ (M = Pd and Pt, R = alkyl or aryl) front K₂MCl₄ (in H₂O) and PR₃ (in CH₂Cl₂) was promoted by the addition of phase-transfer catalysts (PTC). The greater the amount of PTC used, the more quickly the reaction completed. ³¹P NMR spectra of some M(PR₃)₂Cl₂ in the presence of free PR₃ were measured; these NMR resulls were used to explain problems encountered during the preparations.     

Sulfobridged Polynuclear Complexes of Platinum(II) and Palladium(II)

When the platinum(II) and palladium(II) salts interact with ligands such as cystamine-(mercamine) HSCH₂CH₂NH₂ and 2-mercaptoethanol HSCH₂CH₂OH under certain conditions, polynuclear complexes of the compositions are obtained: [Pt₆(SCH₂CH₂NH₂)₈]Cl₄. 5H₂O and [Pd₆(SCH₂CH₂OH)₈]Cl₄. In a comparative study of the IR and X-ray spectra of synthesized complexes and ligands, as well as the results of X-ray diffraction studies, it was established that sulfur atoms of 2-mercaptoethanol occupy a bridge position with a mixed coordination of ligands in the palladium complex. In the platinum(II) complex bidentate coordination of ligands is realized through sulfur and nitrogen atoms.     

Chemistry of N,N-Dimethylaminoalkylchalcogenolate Complexes of Palladium(II) and Platinum(II)

Abstract

Four different series of N,N-dimethylaminoalkylchalcogenolates, viz. Me₂NCH₂ CH₂E^?, Me₂NCH(Me)CH₂E^?, Me₂NCH₂CH(Me)E^?, and Me₂NCH₂CH₂CH₂E^? (E = S, Se, Te), (referred as E^∩N) have been synthesized and characterized. Their reactions with palladium(II) and platinum(II) precursors have been explored. Complexes of the general formula, [MCl(E^∩N)]_n, [MCl(E^∩N)₂]_n, [MCl(E^∩N)(PR₃)], [M₂Cl₂(μ-E^∩N)₂(PR₃)₂], [M₂(μ-E^∩N)₂(P^∩P)₂]²⁺, etc. have been isolated. All the complexes have been characterized by elemental analysis, IR, NMR (¹H, ¹³C, ³¹P, ⁷⁷Se, ¹²⁵Te, ¹⁹⁵Pt), UV-vis, and FAB mass spectral data. A weak absorption in the electronic spectra of [MCl(E^∩N)(PR₃)] has been attributed to metal mediated ligand-to-ligand charge transfer and showed pronounced chalcogen dependence being red shifted on moving from S → Se → Te. Structures of several complexes have been established by X-ray diffraction analyses. Thermal behavior of some of these complexes has been investigated by TGA.     

Carbonyl Complexes of Platinum (II) and Palladium(II) with Heterocyclic Cyclometalating Ligands

Russian Journal of General Chemistry -     

A 13C-NMR. Study of Some Arsenic Complexes of Platinum(II) and Palladium(II)

The ¹³C-NMR. spectra of a series of tri-n-alkyl arsenic complexes of platinum and palladium have been measured. In these complexes it is suggested that the carbon chemical shift of the atom bound directly to the arsenic is a useful structural probe. The chemical shift of the second carbon atom in the chain is interpreted in terms of interactions within the chains of anyone ligand. The values ²J(Pt, C) and ³J(Pt, C) are presented.     

Binuclear Orthometalated N,N-Dimethylbenzylamine Complexes of Palladium(II): Synthesis,Structures and Thermal Behavior

Abstract

Organochalcogenolate-bridged cyclometalated palladium(II) complexes of the formulae, [Pd₂(μ-Epy)₂(Me₂NCH₂C₆H₄-C,N)₂] (2) (E = S (2a), Se (2b)), [Pd₂(μ-SAr)(μ-Cl)(Me₂NCH₂C₆H₄-C,N)₂] (3) (Ar = Ph (3a), Mes (Mes = 2,4,6-Me₃C₆H₂) (3b)) and [Pd₂(μ-SeAr)₂(Me₂NCH₂C₆H₄-C,N)₂] (4) (Ar = Ph (4a), Mes (4b)), have been synthesized by the reactions of [Pd₂(μ-Cl)₂(Me₂NCH₂C₆H₄-C,N)₂] with lead or sodium salts of the chalcogenolate ligand. These complexes have been characterized by elemental analysis, mass spectral data, and NMR (¹H and ⁷⁷Se{¹H}) spectroscopy. The molecular structure of 2, determined by single crystal X-ray diffraction analysis, revealed a Epy-bridged head-to-tail arrangement in which the eight-membered “(PdECN)₂” ring adopts a distorted twist boat conformation. The Pd····Pd separation in 2a is within the van-der-Waals interaction but in 2b it is too large to support the presence of any metal–metal interaction. The thermal behavior of these complexes has been studied by thermogravimetric analysis.     

Metal-Metal Interaction and Flexible Motion of Triple-Decker Polypyridyl Platinum(II) and Palladium(II) Complexes

Triple-decker polypyridyl platinum(II) and palladium(II) complexes were prepared using an N,S-bridging ligand. In solution, tight stacking structures were observed at low temperatures, whereas flexible motion was observed at room temperature. These dynamic behaviors are reflected in the electronic absorption and NMR spectra of these complexes.     

Preparation of Platinum(II) Cyclooctadiene Complexes by Photoirradiation

Preparation of platinum cyclooctadiene complexes under photoirradiation was studied, and the reaction mechanism was suggested.__________Translated from Zhurnal Obshchei Khimii, Vol. 75, No. 3, 2005, pp. 353–356.Original Russian Text Copyright © 2005 by de Vekki, Uvarov, Skvortsov.     

Synthesis and Characterization of Palladium(II) and Platinum(II) Complexes Containing Water-Soluble Hybrid Phosphine-Phosphonate Ligands

Water-soluble phosphonate-functionalized triaryl phosphine ligands Na(2)[Ph(2)P(4-C(6)H(4)PO(3))].1.5H(2)O (4a), Na(2)[Ph(2)P(3-C(6)H(4)PO(3))].2H(2)O (4b), and Na(2)[Ph(2)P(2-C(6)H(4)PO(3))].2H(2)O (4c), were prepared in 54-56% yields by the transesterification and hydrolysis of the appropriate phosphonic acid diethyl ester precursors. The solubilities of 4a-c in water are compared and the spectroscopic properties studied in detail. The crystal structure of Na(2)[Ph(2)P(4-C(6)H(4)PO(3))(H(2)O)(3)(CH(3)OH)].CH(3)OH (monoclinic, P2(1)/n, a = 6.4457(8) ?, b = 8.1226(8) ?, c = 46.351(3) ?, beta = 92.902(8) degrees, Z = 4) shows a dimeric association via two bridging water molecules and four sodium ions. Reaction of 4a with PtCl(2)(PPh(3))(2) in a biphasic H(2)O/CH(2)Cl(2) mixture gives cis- and trans-Na(4)[PtCl(2){Ph(2)P(4-C(6)H(4)PO(3))}(2)]. 3H(2)O. Palladium dichloride and 4a in H(2)O/benzene catalyzes the carbonylation of benzyl chloride to give phenylacetic acid (91%).     

Cationic Palladium(II), Platinum(II), and Rhodium(I) Complexes as Acetalisation Catalysts

The use of [Pd(H₂O)2(Ph₂PCH₂CH₂PPh₂)] (CF₃SO₃)₂ as a catalyst for the acetalisation of a variety of aldehydes and ketones and for trans-acetalisation is described. It is also shown that Pt(H₂O)2(PH₂PCH₂CH₂PPh₂) (CF₃SO₃)₂ is at least as effective as the corresponding Pd compound, while much lower reaction rates are observed with [Rh(MeOH)₂(Ph₂PCH₂CH₂PPh₂)] [BF₄].     

Anionic Palladium(0) and Palladium(II) Ate Complexes

Palladium ate complexes are frequently invoked as important intermediates in Heck and cross‐coupling reactions, but so far have largely eluded characterization at the molecular level. Here, we use electrospray‐ionization mass spectrometry, electrical conductivity measurements, and NMR spectroscopy to show that the electron‐poor catalyst [L₃Pd] (L=tris[3,5‐bis(trifluoromethyl)phenyl]phosphine) readily reacts with Br⁻ ions to afford the anionic, zero‐valent ate complex [L₃PdBr]⁻. In contrast, more‐electron‐rich Pd catalysts display lower tendencies toward the formation of ate complexes. Combining [L₃Pd] with LiI and an aryl iodide substrate (ArI) results in the observation of the Pd^II ate complex [L₂Pd(Ar)I₂]⁻.     

The Preparation, Characterization and Biological Activity of Palladium(II) and Platinum(II) Complexes of Tridentate NNS Ligands Derived from S-methyl- and S-benzyldithiocarbazates and the X-ray Crystal Structure of the [Pd(mpasme)Cl] Complex

New complexes of general formula, [M(NNS)Cl] (M = Pd^II, Pt^II; NNS = anionic forms of the 6-methyl-2-formylpyridine Schiff bases of S-methyl- and S-benzyldithiocarbazates) have been prepared and characterized by a variety of physico-chemical techniques. Based on conductance and spectral evidence, a square-planar structure is assigned to these complexes. The crystal and molecular structure of the [Pd(mpasme)Cl] complex (mpasme=anionic form of the 6-methyl-2-formylpyridine Schiff base of S-methyldithiocarbazate) has been determined by X-ray diffraction. The complex has a distorted square-planar geometry with the ligand coordinated to the palladium(II) ion via the pyridine nitrogen atom, the azomethine nitrogen atom and the thiolate sulfur atom; the fourth coordination position around the palladium(II) ion is occupied by the chloride ligand. The distortion from a regular square-planar geometry is ascribed to the restricted bite angle of the ligand. Both the Schiff bases exhibit strong cytotoxicity against the human ovarian cancer (Caov-3) cell lines, the S-methyl derivative being two times more active than the S-benzyl derivative. The [Pt(mpasme)Cl] complex is moderately active but the palladium(II) complex is weakly active against this cancer. None of the complexes of Hmpsbz are active against Caov-3. The Schiff base, Hmpasme exhibits moderate activity against the bacteria, MRSA, P. aeruginosa and S. typhimurium but is inactive against B. subtilis. Coordination of the ligand with palladium(II) substantially reduces its activity. The Schiff base, Hmpasbz and its palladium(II) and platinum(II) complexes are inactive against these bacteria. The Schiff bases and their palladium(II) and platinum (II) complexes are inactive against the pathogenic fungi, C. albican, Aspergillus ochraceous and Saccharomyces cerevisiae.     

Tripropylarsane Complexes of Palladium(II) and Platinum(II) — Syntheses,Spectroscopy, and Structures

Several palladium(II) and platinum(II) complexes of tripropylarsanes (AsR₃; R = Pr, iPr) with the formulae, [MCl₂(AsR₃)₂], [M₂Cl₂(μ‐Cl)₂(AsR₃)₂], [Pd₂Me₂(μ‐Cl)₂(AsR₃)₂], [Pd₂X₂(μ‐Pz)₂(AsR₃)₂] (X = Cl or Me, Pz = pyrazolate), [Pd₂Cl₂(μ‐Y)₂(AsR₃)₂] (Y = OAc or SPh), [MCl(S₂CNEt₂)(AsR₃)] and [PdCp(Cl)(AsiPr₃)] (M = Pd or Pt) have been prepared. All the complexes have been characterised by elemental analyses, IR and ¹H NMR spectroscopy. The stereochemistry of the complexes has been deduced from the spectroscopic data. The structures of [Pd₂Me₂(μ‐X)₂(AsiPr₃)₂] (X = Cl or Pz) have been established by single crystal X‐ray diffraction analyses. Both of the complexes have sym‐trans configuration. Strong trans influence of the methyl group is reflected on the Pd—X bond distances.     

Interaction of Dinitrogentrioxide with Platinum(0) and Palladium(0) Complexes

Dinitrogentrioxide reacts with tetrakis(triphenylphosphine) platinum and palladium under nitrogen to give dinitrobis(triphenylphosphine) platinum(II) and palladium(II) complexes, respectively. In the presence of oxygen these reactions afford the formation of nitro-nitrato complexes of platinum(II) and palladium(II). The products are characterized by the elemental analyses, i.r. spectra, conductivity and magnetic measurements.     

Synthesis,Characterization, and Non-Covalent Interactions of Palladium(II)-Amino Acid Complexes

The reaction of palladium(II) acetate with acyclic amino acids in acetone/water yields square planar bis-chelated palladium amino acid complexes that exhibit interesting non-covalent interactions. In all cases, complexes were examined by multiple spectroscopic techniques, especially HRMS (high resolution mass spectrometry), IR (infrared spectroscopy), and ¹H NMR (nuclear magnetic resonance) spectroscopy. In some cases, suitable crystals for single crystal X-ray diffraction were able to be grown and the molecular structure was obtained. The molecular geometries of the products are discussed. Except for the alanine complex, all complexes incorporate water molecules into the extended lattice and exhibit N-H···O and/or O···(HOH)···O hydrogen bonding interactions. The non-covalent interactions are discussed in terms of the extended lattice structures exhibited by the structures.     

Cyanoalkyl Complexes of Platinum (II). I. Preparation and Spectroscopic Properties

The oxidative addition of XRCN to PtL₄ yields cis-and/or trans-PtX(RCN)L₂ (X = Cl, Br; R = (CH₂)_n, n = 1, 2, 3; L = PPh₃, PPh₂CH₃, AsPh₃). L is readily displaced by more basic phosphines or by a diphosphine. In each case the trans complex is the thermodynamically more stable isomer and cis-trans isomerization catalyzed by free L occurs in dichloromethane. Insertion of CO in the σ Pt? C bond takes place quantitatively in the case of cyanoethyl and cyanopropyl. Abstraction of X by AgBF₄ gives cis or trans cationic complexes with N-bonded CN group.     

Metal Complexes of Biologically Important Ligands,CLXXVII. Dichlorido Platinum(II) and Palladium(II) Complexes with Long Chain Amino Acids and Amino Acid Amides

The synthesis of Cl₂Pt[NH₂(CH₂)_nCOOH]₂ (n = 5, 10) and the reactions of their carboxylic groups with H₂N(CH₂)₁₇CH₃, d ‐glucosamine, and (R,R)‐1,2‐diaminocyclohexane to give complexes with amino acid amides as ligands, are reported. Cl₂Pd(histidine) is coupled with amino alcohols to give Cl₂Pd(histidineamide) complexes.