Radical intermediates in hydrogenation of aromatic nitro compounds in presence of platinum(ii) complex with alizarin

Conclusions The particles, obtained by the reduction of the Pt(II)-alizarin complex with H₂ and subsequent reaction with sym-trinitrobenzene, have a radical nature.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 4, pp. 924–925, April, 1981.     

Mono- and bimetallic platinum(II) and palladium(II) complexes containing fluorinated benzothiolates

The new mononuclear palladium(II) and platinum(II) [M(p-SC₆F₄(CF₃))₂(dppe)] complexes M = Pd 1a, Pt 2a; [M(o-SC₆H₄(CF₃))₂(dppe)] M = Pd 1d, Pt 2d as well as the previously known [M(SC₆F₅)₂(dppe)] M = Pd 1b, Pt 2b and [M(p-SC₆HF₄)₂(dppe)] M = Pd 1c, Pt 2c, have been used as metalloligands for the preparation of the heteroleptic bimetallic complexes [M₂(μ-SRf)₂(dppe)₂](SO₃CF₃)₂ M = Pd, Rf = p-C₆F₄(CF₃) 3a, C₆F₅3b, p-C₆HF₄3c, o-C₆H₄(CF₃) 3d; M = Pt, Rf = p-C₆F₄(CF₃) 4a, C₆F₅4b, p-C₆HF₄4c and o-C₆H₄(CF₃) 4d. Variable temperature ¹⁹F NMR experiments show that the fluorothiolate bridged bimetallic compounds are fluxional in solution whereas mononuclear complexes are not. The solid state X-ray diffraction structures of [Pd(p-SC₆HF₄)₂(dppe)] (1c), [Pt(SC₆F₅)₂(dppe)] (2b) and [Pt(o-SC₆H₄(CF₃))₂(dppe)] (2d) show square-planar coordination around the metal centers. The solid state molecular structure of the compound [Pt₂(μ-o-SC₆H₄(CF₃))₂(dppe)₂](SO₃CF₃)₂ (4d), exhibit a planar [Pt₂(μ-S)₂] ring with the sulfur substituents in an anti configuration.     

N-aminorhodamne complexes of palladium(II), palladium(IV) and platinum(II)

Summary TheN-aminorhodanine (L) complexes: PdLX, (X = Br or I), ML_1.5Cl₂ (M = Pd or Pt), PtL₂X₂ (X = Br, I or ClO₄), PdL₃(ClO₄)₂, PdL_1.5Cl₄ and PdL₃(ClO₄)₄ have been prepared and investigated. The ligand is bonded to the metal ion through the aminic nitrogen atom as monodentate or through this atom and the thiocarbonylic sulphur atom when it acts as chelating or bridging ligand. The carbonylic oxygen atom is never coordinated.     

Some palladium(II) and platinum(II) lead bonded complexes

Complexes of the type M(PPh₃)₂(PbPh₃)₂ [M = Pd, (Ia) and Pt, (Ib)] have been prepared by oxidative addition of hexaphenyldilead to M(PPh₃)₄. The compound Pt(PPh₃)₂(PbPh₃)₂, (Ib), slowly decomposes in dichloromethane to give cis-Pt(PPh₃)₂(PbPh₃)Ph, (II). which can also be obtained by treating (Ib) with the stoichiometric amount of LiPh. Reaction of Pt(PPh₃)₄ with hexamethyldidead gives the complex Pt(PPh₃)₂(PbMe₃)Me directly.The MPb bonds are easily cleaved by bromine, iodine and hydrogen bromide. The X-ray structure of (II) has been determined using three-dimensional counter data and refined by the least-square method (R = 0.07). The crystals are monoclinic a = 22.501, b = 10.502, c = 24.120 Å, β = 113.43°, space group P2₁/c with Z = 4. The complex exhibits a cis configuration, with the coordination around the platinum atom essentially square-planar: the PtPb and PtC(phenyl)bond lengths are 2.698(1) and 2.055(3)Å, respectively.     

Reduction of nitrobenzene in the liquid phase by carbon monoxide (II) in the presence of palladium complexes

Conclusions We investigated the transformations of catalysts based on palladium complexes under the conditions of the catalytic reduction of nitrobenzene by carbon monoxide (II). We established that the reduced forms of the catalyst are Pd₂(PPh₃),₄(CO)·H₂SO₄ and Pd₂PPh₃)₄CO)· HClO₄, while the reduced forms are Pd(PPh₃)₂SO₄ and Pd(PPh₃)₃(H₂O)(ClO₄)₂ in the sulfate and the perchlorate media, respectively.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 5, pp. 998–1002, May, 1989.     

Carbamoyl and alkoxycarbonyl complexes of palladium(II) and platinum(II)

Carbamoyl and alkoxycarbonyl complexes of palladium(II) and platinum(II) of the type M(pnp)(CONHR)Cl (pnp = 2,6-bis(diphenylphosphinomethyl)pyridine; M Pd, R  C₆H₅, p-CH₃C₆H₄, p-CH₃OC₆H₄, C₆H₁₁, t-Bu; M  Pt, R  C₆H₅), Pd(pnp)[CON(Pr)₂]Cl (Pr = propyl), M(pnp)(COOR)Cl (M  Pd, R  C₆H₅, CH₃; M  Pt, R  CH₃), Pd(pnp)(COOCH₃)₂ result from reaction of M(pnp)Cl₂ with carbon monoxide and amines or alkoxides at room temperature and atmospheric pressure.The carbamoyl complexes react with bases to give urethane or diphenylurea depending upon the experimental conditions.     

Cationic palladium(II), platinum(II) and ruthenium(II) complexes containing a chelating difluoro-substituted thiourea ligand

The fluorine substituted thiourea 2,6-F₂C₆H₃C(O)NHC(S)NEt₂ was prepared in good yield from the reaction of 2,6-F₂C₆H₃C(O)Cl with KSCN and Et₂NH in acetone. Using this compound several heteroleptic, monocationic Pd(II), Pt(II) and Ru(II) complexes of the type cis-[M{κ²S,O-2,6-F₂C₆H₃C(O)NC(S)NEt₂}(L)]PF₆ [M = Pt, Pd; L = (Ph₃P)₂, ^tBu₂bipy, 1,10-phen] as well as [Ru(η⁶-p-cym){κ²S,O-2,6-F₂C₆H₃C(O)NC(S)NEt₂}(PPh₃)]PF₆ were prepared in high yields. The compounds were characterised by spectroscopic methods and, in one case, by single crystal X-ray diffraction.     

Synthesis, spectroscopy and structures of palladium(II) and platinum(II) complexes containing mercapto-o-carborane

The reactions of [M₂Cl₂(μ-Cl)₂(PMe₂Ph)₂] with mercapto-o-carboranes in the presence of pyridine afforded mono-nuclear complexes of composition, [MCl(SCb°R)(py)(PMe₂Ph)] (M = Pd or Pt; Cb° = o-C₂B₁₀H₁₀; R = H or Ph). The treatment of [PdCl₂(PEt₃)₂] with PhCb°SH yielded trans-[Pd(SCb°Ph)₂(PEt₃)₂] (4) which when left in solution in the presence of pyridine gave another substitution product, [Pd(SCb°Ph)₂(py)(PEt₃)] (5). The structures of [PdCl(SCb°Ph)(py)(PMe₂Ph)] (1), [Pd(SCb°Ph)₂(PEt₃)₂] (4) and [Pd(SCb^oPh)₂(py)(PEt₃)] (5) were established unambiguously by X-ray crystallography. The palladium atom in these complexes adopts a distorted square-planar configuration with neutral donor atoms occupying the trans positions. Thermolysis of [PdCl(SCb°)(py)(PMe₂Ph)] (2) in TOPO (trioctylphosphine oxide) at 200 °C gave nanocrystals of TOPO capped Pd₄S which were characterized by XRD pattern and SEM.     

The chemistry of binuclear palladium(II) and platinum(II) complexes

The chemistry of binuclear palladium(II) and platinum(II) complexes has been reviewed. This review deals with complexes derived from various classes of ligands and covers various aspects, viz. synthesis, spectroscopic and structural features and chemical reactivity, of these complexes. Applications of these complexes are briefly described in the respected sections.     

Hydrogenation of cyclopropylbenzene in presence of palladium and platinum blacks

Summary Substantial differences were found in the course of reaction in the hydrogenation of cyclopropylbenzene in the presence of platinum and palladium blacks.     

New biimidazole and bibenzimidazole derivatives: mono and binuclear palladium(II) or platinum(II) complexes and heterobinuclear palladium(II)-rhodium(I) or platinum(II)-rhodium(I) complexes

Novel neutral biimidazolate or bibenzimidazolate palladium(II) and platinum(II) complexes of the type M(NN)₂(dpe) [M = Pd, Pt; (NN)₂^2? = BiIm^2?, BiBzIm^2?. dpe = 1,2-bis(diphenylphosphino) ethane] have been obtained by reacting MCl₂(dpe) with TI₂(NN)₂. Complexes M(NN)₂(dpe) which are Lewis bases react with HClO₄ or [M(dpe)(Me₂CO)₂](ClO₄)₂ to yield, respectively, mononuclear cationic complexes of general formula [M{H₂(NN)₂](dpe) (M = Pd, Pt; H₂(NN)₂ = H₂BiIm, H₂BiBzIm) and homobinuclear palladium(II) or platinum(II) cationic complexes of the type [M₂{μ - (NN)₂}(dpe)₂](ClO₄)₂. Reactions of M(BiBzIm)(dpe) with [Rh(COD) (Me₂CO)_X](ClO₄) render similar heterobinuclear palladium(II)-rhodium(I) and platinum(II)-rhodium(I) cationic complexes, of general formula [(dpe)M(μ-BiBzIm)Rh(COD)](ClO₄) (M = Pd, Pt; COD = 1,5-cyclooctadiene). Di- and mono-carbonyl derivatives [(dpe)M(μ-BiBzIm)Rh(CO)L](ClO₄) (M = Pd, Pt; L = CO, PPh₃) have also been prepared. The structures of the resulting complexes have been elucidated by conductance studies and IR spectroscopy.     

Synthesis and characterization of palladium(II) and platinum(II) complexes with ferrocenylimidazole

The synthesis and characterization of ferrocenylimidazole complexes of platinum(II) and palladium(II) are described. Reaction of ferrocenylimidazoles with K₂MCl₄ (M = Pd, Pt) using a biphasic system of dichloromethane and ethanol/water provided the corresponding complexes 2a–2j in good yields. New synthetic routes for the synthesis of ferrocenylbenzylethers 2k–2o, bis(4-ferrocenylbenzyl)carbonate [2p] and 4-ferrocenylbenzylacetate [2q] are also described. These products were obtained by the reaction of 4-ferrocenylbenzyl-1H-imidazole-carboxylate and K₂PtCl₄ under various conditions. Compounds 2k–2o were also obtained by alternative routes which do not involve the use of a platinum salt. The crystal structures of 2b, 2q and plausible mechanisms for the formation of 2k, 2p and 2q are reported.     

The chemistry of tri- and high-nuclearity palladium(II) and platinum(II) complexes

This review gives an overview of the progress on tri- and high-nuclearity palladium(II) platinum(II) complexes and discusses recent developments in the chemistry of these complexes. Three or more square-planar metal atoms can be assembled in several ways resulting into myriad geometric forms of the resulting complexes. These square planes may be sharing a corner, an edge and two edges or even separated by ligands having their donor atoms incapable of forming chelates yielding dendrimers and self-assembled molecules. A variety of ligands have been used to stabilize these complexes. The chemistry of these complexes has been dealt based on nuclearity of the complexes. Synthetic, spectroscopic, structural aspects and applications of these complexes are described in this review.     

Bonding modes of nitrite and nitrate in palladium(II) and platinum(II) complexes

The crystal structures of the well-known complexes, [(Me₄en)M(II)X₂] (Me₄en?=?N,N,N??,N??-tetramethylethylenediamine; M(II)?=?Pd(II) or Pt(II); X ^??=?NO₂ ^? or NO₃ ^?) have been determined. For [(Me₄en)Pd(NO₂)₂] and [(Me₄en)Pt(NO₂)₂], the nitrite anion acts as a monodentate N-donor ligand in the solid state. In contrast, for [(Me₄en)Pd(ONO₂)(O₂NO)], the two nitrate anions act as a monodentate O-donor (ONO₂) and a bidentate O,O??-donor (O₂NO). Recrystallization of [(Me₄en)Pt(NO₃)₂] from Me₂SO yields the Me₂SO adduct with a monodentate O-donor nitrate and a counteranionic nitrate, [(Me₄en)Pt(ONO₂)(S-Me₂SO)](NO₃). The solution behavior of these complexes, including the equilibrium between coordinated and free Me₂SO, has been investigated.     

Structural investigations of palladium(II) and platinum(II) complexes of salicylhydroxamic acid

Complexes of salicylhydroxamic acid (shaH) with palladium(II) and platinum(II) were investigated. The synthesis of [Pt(sha)(2)] was attempted via a number of methods, and ultimately (1)H NMR investigations revealed that salicylhydroxamate would not coordinate to chloro complexes of platinum(II). However, [Pt(sha-H)(PPh(3))(2)] was successfully synthesized and the crystal structure determined (orthorhombic, space group Pca2(1) a = 17.9325(19) A, b = 11.3102(12) A, c = 18.2829(19) A, Z = 4, R = 0.0224). The sha binds via an [O,O] binding mode, in its hydroximate form. In contrast the palladium complex [Pd(sha)(2)] was readily synthesized and crystallized as [Pd(sha)(2)](DMF)(4) in the triclinic space group P(-)1,a = 7.066(1) A, b = 9.842(2) A, c = 12.385(2) A, alpha = 99.213(3)(o), beta = 90.669(3), gamma = 109.767(3)(o), Z = 1, R = 0.037. The unexpected [N,O'] binding mode of the salicylhydroxamate ligand in [Pd(sha)(2)] prompted investigation of the stability of a number of binding modes of salicylhydroxamic acid in [M(sha)(2)] (M = Pd, Pt) by density functional theory, using the B3LYP hybrid functional at the 6-311G* level of theory. Geometry optimizations were carried out for various binding modes of the ligands and their relative energies established. It was found that the [N,O'] mode gave the more stable complex, in accord with experimental observations. Stabilization of hydroxamate binding to platinum is evidently afforded by soft ligands lying trans to them.     

Preparation of cationic chelate ylide complexes of palladium(II) and platinum(II)

Cationic palladium(II) and platinum(II) complexes with chelate ylides and neutral ligands of the type, [MCl (Y) (L)]⁺BPh₄^? (M  Pd or Pt; Y  bdep or bdmp*; L = 4-methylpyridine, 3,5-dimethylpyrazole, PPh₃, PCy₃, PMePh₂, P(OMe)₃, AsPh₃ or SbPh₃) and [M(bdep) (4-methylpyridine)₂] (BPh₄)₂ (M = Pd or Pt) were prepared and characterized by means of infrared and ¹H NMR spectra.