Oxidation of bridging groups by carboxylate coordinated ligands in palladium clusters

Thermolysis of tetranuclear palladium clusters Pd₄(-Q)₄ Pd₄(-Q)₄(-O₂CR)₄ (Q=CPh₂ or CO;R=Me, CMe₃, Ph, CH₂Cl or CF₃) has been found to involve innersphere oxidation of carbene or carbonyl ligands during which an oxygen atom transfer occurs from the carboxylate group to the carbene or carbonyl ligand. The thermolysis of the carbonyl clusters gives rise to the products of CO₂ insertion into the C–H bond of benzene or toluene used as solvents forming benzoic acid from benzene and a mixture of phenylacetic and toluic acids from toluene. The reaction of [Pd(OAc)₂(PPh₃)]₂ with HCO₂H includes the transfer of an O atom from formate ligand to the P atom and cleavage of the P-Ph bond accompanied by transfer of the Ph group from PPh₃ ligand to the palladium atom. The structure of the complex formed, [Pd(-O₂PPh₂)(C₆H₅)(PPh₃)]₂, has been resolved by X-ray analysis.     

NO-disproportionation, promoted by Pd-cluster: formation and X-ray structure of Pd8(micro-CO)4(micro-OOCCMe3)8[micro-N(=O)O-]4

Interaction of Pd-clusters [Pd(CO)(OCOR)](n) with NO was investigated, these Pd-clusters were found to promote the NO disproportionation into N(2) and NO(2)(-) in mild conditions; an eight-nuclear palladium cluster Pd(8)(micro-CO)(4)(micro-OOCCMe(3))(8)(micro-NO(2))(4) with a new type of structure and an uncommon set of ligands was characterized by X-ray diffraction analysis.     

Interaction of polynuclear palladium (I) carbonyl carboxylates with gaseous NO: X-ray structure of eight-nuclear clusters Pd8(μ-CO)4(μ-OOCR)4[μ-N(O)O–]4

The reaction of palladium carbonyl carboxylates Pd₆(CO)₆(RCOO)₆ with gaseous nitrogen monoxide was investigated. These clusters were found to promote the NO disproportionation into N₂ and NO₂ under mild conditions. The reaction is accompanied with the oxidation of coordinated carbon monoxide. These processes result in unusual eight-nuclear palladium carboxylate clusters Pd₈(CO)₄(NO₂)₄(RCOO)₈.     

Metallation of the methyl group ino-nitrosotoluene: synthesis and the molecular structure of the binuclear complex [o-(NO)(CH2)C6H4)]2Pd2(μ-OOCCF3)2

The reaction of the tetranuclear cluster Pd₄(CO)₄(OOCCF₃)₄ witho-nitrosotoluene afforded the Pd¹¹-containing complex [o-(NO)(CH₂)C₆H₄]₂Pd₂(μ-OOCCF₃)₂. The elimination of CO₂ and the formation of organic products of transformation of tolylnitrene species (azotoluene, ditolylamine, and tolylisocyanate) were observed in the course of the reaction. The title complex was characterized by IR and¹H NMR spectroscopy. Its structure was established by X-ray diffraction analysis. It was suggested that the reaction proceeds through intermediate formation of nitrene complexes. Translated fromIzvestiya Akademii Nauk. Seriya Khimicheskaya, No. 1, pp. 147–150, January, 2000.     

Reduction of nitrosoarene ligands in binuclear palladium(ii) complexes

Reduction of the binuclear Pd^II complexes Pd₂(OCOR)₂(o-CH₂C₆H₄—NO)₂ (1) and Pd₂(OCOR)₂(o-PhN—C₆H₄—NO)₂ (2) (where R = Me, CF₃, Bu^t, or Ph) by sodium borohydride, an ethanolic solution of KOH, or molecular hydrogen was examined. The first stage of reduction was demonstrated to afford metallic palladium and aromatic amines, viz., o-toluidine o-Me—C₆H₄—NH₂ from complex 1 and aniline Ph—NH₂ from complex 2. The reactions with molecular hydrogen involve deeper stages to yield cyclic ketones (o-methylcyclohexanone and cyclohexanone) and then cycloalkanes (methylcyclohexane and cyclohexane, respectively). The latter reactions are accompanied by elimination of N₂. The mechanism of reduction of complexes 1 and 2 with molecular hydrogen was proposed.     

Palladium acetate complexes with morpholine and 4-methylmorpholine. The structure of Pd(C4H9ON)2(OAc)2 · 2H2O

Methods for the synthesis of new palladium(II) acetate complexes [L₂Pd(OCOCH₃)₂], where L is N-coordinated morpholine (C₄H₉ON) or 4-methylmorpholine (C₅H₁₁ON), have been developed. The structure of the complex (C₄H₉ON)₂Pd(OAc)₂ · 2H₂O (1) has been established by X-ray diffraction. The crystals of 1 are monoclinic (C₁₂H₂₆O₈N₂Pd, M = 434.76), space group P2(1)/c, a = 9.129(3) Å, b = 16.227(5) Å, c = 6.159(2) Å, V = 878.5(5) ų, Z = 2. The palladium atom has a square-planar environment with the trans arrangement of ligands. The complex (C₅H₁₁ON)₂Pd(OAc)₂ (2) has a similar structure, according to spectroscopic data.