90 research outputs found
Supported catalysts from polymerizable transition metal complexes
No full textThis review covers the last 12 years of research on the synthesis and use of heterogeneous catalysts obtained by co-polymerization of suitable metal containing monomers (MCM). The catalytic applications of these supported metal complexes are subdivided into three areas. Hydrogenation of alkenes and functionalized olefins are covered first. Oxidation of several substrates such as olefins, sulfides, alcohols, and aldehydes are then considered. Of particular interest in this framework is the use of chiral salen metal containing monomers for the stereoselective epoxidation of hindered olefins. Alkene and alkyne polymerizations, Heck and Heck-type reactions, allylic alkylation, and Michael additions are discussed in the field of carbon-carbon bond forming reactions. A common factor emerging from this survey is the application of metal containing monomers for the synthesis of molecularly imprinted polymers to be used as catalysts or catalyst supports
Catalytic activity of a polymerizable tris(β-ketoesterate)iron(III) complex towards the oxidation of organic substrates
No full textThe facile oxidation of alkenes, aldehydes, cyclic ketones, alkanes, sulfides and alcohols is achieved by a polymerizable β-ketoesterato complex under Mukaiyama's conditions (atmospheric pressure of molecular oxygen in the presence of a sacrificial aldehyde at room temperature)
Cobalt(II) and iron(III) complexes with 2-(acetoacetoxy)ethylmethacrylate: potential precursors of hybrid catalysts
No full textThe synthesis and characterization of homo- and heteroleptic β-ketoesterate complexes of cobalt(II) and iron(III) by reaction of their nitrates and/or acetates with 2-(acetoacetoxy)ethylmethacrylate (HAAEMA) is described. The obtained complexes bear non-coordinated carbon-carbon double bonds and are therefore potential precursors of hybrid catalysts. The homoleptic Co(AAEMA)2 and Fe(AAEMA)3 complexes are obtained when Co(NO3)2 or Fe(NO3)3 reacts in alkaline medium with HAAEMA whereas the heteroleptic Co(AAEMA)(AcO) complex is formed starting from Co(AcO)2 and HAAEMA
The reactivity of Ni(II)-tertiary phosphine complexes towards alkoxides under carbon monoxide: methoxo-carbonyl complexes, synthesis and reactivity
No full textThe reactivity of some Ni(II)-tertiary phosphine complexes, NiX2L2 (X=Cl, Br, I; L=tertiary alkylphosphine), towards the RONa (R=Me, Et, Ph, PhCH2) alkoxides under carbon monoxide, has been studied. Whereas their reactions with methoxide yield trans-NiXL2COOCH3 methoxo-carbonyl complexes, those with the other alkoxides lead to the formation of organic and inorganic products such as aldehydes, hydrocarbons, CO2 or derivatives, Ni(II) and Ni(0) compounds. This behaviour could be explained by assuming that the reactions lead to the formation of unstable NiXL2(OR) alkoxo complexes, which can either react with CO to yield the alkoxo-carbonyls NiXL2COOR, or else decompose to Ni compounds and organic products. The alkoxo complexes have not been isolated but in some cases spectroscopic evidence of their formation has been obtained. Furthermore, we have studied the reactivity of methoxo-carbonyl complexes towards amines and alkoxides: under CO they are not very reactive either in mild or in drastic conditions, and above all yield compounds which derive from decarbonylative and decarboxylative decomposition
Hydrogenation of ethyl 12-trimethylsilyl-9-dodecyn-11-enoate by isocyanide polymer-bound Rh(PPh3)3Cl
No full textThe E-isomer of the title substrate has been hydrogenated with 75% selectivity to the corresponding Z, E-diene at 4.5 bar H-2 and room temperature in the presence of catalytic amounts of a polymer bound rhodium complex
Aerobic oxidation of trivalent phosphorus and arsenic compounds in the presence of 3-methylbutanal and metal catalyst
No full textThe oxidation of alkyl and aryl phosphines, tryphenylphosphite and triphenylarsine was achieved using oxygen or air as the oxidant in the presence of excess 3-methylbutanal and catalytic amount Co(acac)2. Tests carried out with a heterogeneous analogue of Co(acac)2 revealed that the supported cobalt polymer acts as an active and reusable catalyst in the oxidation of triphenylphosphine
Synthesis and characterization of the neutral dinuclear hydrido complexes of platinum with bridging phosphides cis-Pt2(H)2(PHBut2)2(μ-H)(μ-PBut2) (Pt–Pt) and trans-[Pt(H)(PHBut2)(μ-PBut2)]2 (Pt–Pt)
No full texttrans-PtCl2(PHBut2)21 reacts with NaBH4 in THF affording the dinuclear platinum(II) complexes cis-Pt2(H)2(PHBut2)2(μ-H)(μ-PBut2) (Pt–Pt) 2 and trans-[Pt(H)(PHBut2)(μ-PBut2)]2 (Pt–Pt) 3 along with the boron adduct BH3·PHBut24. Pure 2 can be obtained in 85% yield in the reaction carried out in the presence of two equivalents of di-tert-butylphosphine
Carbon dioxide-transition metal complexes. IV. New Ni(0)CO2 complexes with chelating diphosphines: influence of PNiP angle on complex stabilities
No full textThe reaction between Ni(0) complexes (dp) (dp = 1,2-bis(dicyclohexylphosphino)ethane, 1,3-bis(dicyclohexylphosphino)propane, 1,4-bis(dicyclohexylphosphino)butane; dcpe, dcpp, dcpb, respectively) and carbon dioxide is described. The influence of the PNiP bond angle on the stability of the corresponding adducts is discussed. The reactions of Ni(dcpp)CO2 and Ni(dcpb)CO2 with dioxygen are also described
Reaction of Nickel(II) and Palladium(II) with Tetraphenyldiphosphine
No full textThe reaction of tetraphenyldiphosphine with NiCl2 and Pd(PhCN)2Cl2 was investigated. Aquo or alcohol complexes of nickel(II) chloride afforded Ni(PPh2H)4 whereas anhydrous NiCl2 in aromatic solvents facilitated the decomposition of the diphosphine into triphenylphosphine and diphenylphosphine. Pd(PhCN)2Cl2 gave rise to Pd(Ph2P-PPh2)Cl2
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