Acetylacetone palladium complexes

Palladium, polymethylenebis(diphenylphosphine)-bis(thiocyanato)-linkage isomers, 1, 185 Palladium, tetraammine-tetrachloropalladate history, 1, 2 Palladium, tetrachloro-crystal structure, 1, 16 Palladium, tris(dinitrogen)-synthesis, 1,28 Palladium complexes a,(5-dione dioximates electrical properties, 6, 143 acetylacetone hydrolysis, 2,379 alkylperoxo... 

A detailed stu of over 45 catalysts, primarily from Group VIII metal salts and complexes, showed palladium(II) compounds to be the most effective in the dehydrogenation of a variety of aldehydes and ketones. Soluble palladium(II) salts and complexes such as dichloro(tTiphenylphosphine)palladium(II) and palladium(II) acetylacetonate have been shown to be optimal, with the salts of rhodium, osmium, iridium and platinum having reduced efficacy. Since the d ydrogenation reaction is accompanied by reduction of the palladium(II) catalyst to palladium(0), oxygen and a cooxidant are required to effect reoxidadon. Copper(II) salts are favored cooxidants, but quinones, and especially p-benzoquinone, are also effective (Scheme 24). - ... 

Reactions of acetylacetonates with silica are not as general as with alumina. Cu(acac)2 is adsorbed on the silica in high concentrations while the platinum and palladium complexes do not interact with the silica at all and are easily removed by washing. No adequate explanation of these differences was proposed. 3 palladium acetylacetonate complex was also used for the... 

The chelated metal ion does not seem to affect the pathway of the nitration reactions, but does have an effect on their course. The reaction of nickel(II) acetylacetonate with nitrous acid in water, ethanol, or ethanol-water solutions in the presence of ammonium acetate gave a red compound, N CsHjNsChK which was diamagnetic, monomeric in chloroform solution, and a nonelectrolyte in nitrobenzene. A similar compound was obtained with Pd(II), and the presence of ammonia was found to be essential for the formation of these two compounds. The corresponding compounds of Cu(II) and Pt(II) could not be prepared under the same experimental conditions. The infrared spectra of the nickel and palladium complexes are compatible with the two structures (XII) and (XIII), and on this evidence... 

Preparation of 4-methylacetophenone in the presence of a fluorous acetylacetonate palladium complex... 

A similar complex could be isolated by the reaction of palladiumbis-(acetylacetonate) with two moles of triisopropyl phosphine and two moles of 6-lactone (Equation 7). By ring opening of the lactone a palladium complex with two long-chain carboxylate substituents was formed. It is remarkable that the same ring opening reaction which is discussed in the catalytic cycle could be observed in a related stoichiometric experiment. 

C2ftH3u02Pd, dihapto-Cyclopentadiene-acetylacetone-palladium complex, 39B, 570... 

The palladium(ii) acetylacetonate-tri phenyl phosphine catalysed reaction of butadiene with water and carbon dioxide in solvents such as t-butanol or acetone has been reported to give octa-2,7-dien-l-ol as the major product together with minor amounts of octa-l,7-dien-3-ol, 1,3,7-octatriene and octadienyl ethers. In contrast aqueous potassium tetrachloropalladate with excess diene leads to pale yellow solids which were polymeric. Decomposition of these complexes with dimethylglyoxime gave a mixture of 3-methyIbutenyl ethers, (Scheme 33). The use of (—)-2,2-dimethyl-4,5-bis(diphenylphosphinomethyl)-l,3-dioxolane (DIOP) as a chiral ligand... 

Pd-trioctylphosphine (TOP) complex using palladium(II) acetylacetonate as a precursor. By heating the complex to 300 C and aging for 30 min in the presence of free TOP, a black colloidal solution was formed. It was proposed that the CO molecules generated in situ from the thermal decomposition of acetylacetonate served as reductants. This procedure yielded monodisperse Pd nanoparticles of 3.5 nm or 5 nm diameter (Figure 9.4). 

Also increasingly common, as CVD precursors, are many halogen-acetylacetonate complexes, such as trifluoro-acetylacetonate thorium, Th(C5H4F302)4, used in the deposition of thoriated tungsten for thermionic emitters, the trifluoro-acetylacetonates of hafnium and zirconium and the hexafluoro-acetylacetonates of calcium, copper, magnesium, palladium, strontium, and yttrium. 

In the early work on the thermolysis of metal complexes for the synthesis of metal nanoparticles, the precursor carbonyl complex of transition metals, e.g., Co2(CO)8, in organic solvent functions as a metal source of nanoparticles and thermally decomposes in the presence of various polymers to afford polymer-protected metal nanoparticles under relatively mild conditions [1-3]. Particle sizes depend on the kind of polymers, ranging from 5 to >100 nm. The particle size distribution sometimes became wide. Other cobalt, iron [4], nickel [5], rhodium, iridium, rutheniuim, osmium, palladium, and platinum nanoparticles stabilized by polymers have been prepared by similar thermolysis procedures. Besides carbonyl complexes, palladium acetate, palladium acetylacetonate, and platinum acetylac-etonate were also used as a precursor complex in organic solvents like methyl-wo-butylketone [6-9]. These results proposed facile preparative method of metal nanoparticles. However, it may be considered that the size-regulated preparation of metal nanoparticles by thermolysis procedure should be conducted under the limited condition. 

In the above structure, if Ph3P is replaced by a bidentate ligand such as bipyridyl, there results a C-rj, -acetylacetonate complex in which palladium is tr-bonded to a terminal CH2 group. These presumably exist as tautomeric keto and enol forms (equation l).53... 

Hydrolysis of Pd(MeCOCHMe)2 in aqueous methanol is considered to involve Pd(0,0-MeCOCHCOMe)(0-MeCOCHCOMe)(MeOH) as an intermediate from which the monodentate acetylacetonate ligand is then solvolyzed.221 Subsequent studies on Lewis base complexes of palladium bis(diketonate) complexes provide ample support for the proposed intermediate. A pulse radiolysis study of the kinetics of aquation of M(MeCOCHCOMe) " (M = Cr, Co) indicates that an 17,-172 equilibrium involving one or more of the acetylacetonate ligands occurs, associated with an acid-catalyzed removal of the monodentate ligand.222 Treatment of Cu(MeCOCHCOMe)2 with picric acid in moist dichloromethane affords a partially hydrolyzed material, Cu(MeCOCHC-0Me)(H20)2[C6H2(N02)30], proposed to contain square pyramidal five-coordinate copper with the oxygen atom from the picrate moiety at the apex.223... 

Palladium compounds have also been reported to stabilize unexposed areas to heat.199 The compounds disclosed include the complexes of triphenylphosphine, bipyridine, acetylacetone and dimethylglyoxime. Preferred compounds appear to be the acac analogs. 

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