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International audience; Palladium catalysts supported on acidic fluorinated magnesium hydroxide Pd/MgF2x(OH)x were prepared through precipitation or impregnation methods. Applications to the hydrogenation of various aldimines and ketimines resulted in good catalytic activities at mild temperatures using one atmosphere of hydrogen. Quinolines, pyridines and other Nheterocycles were successfully hydrogenated at higher temperature and hydrogen pressure using low palladium loadings and without the use of any acid additive. Such reactivity trend confirmed the positive effect of the Brønsted and Lewis acid sites from the fluorinated magnesium hydroxide support resulting in the effective pre-activation of N-heterocycle substrates and therefore in the good catalytic activity of the palladium nanoparticles during the hydrogenations. As demonstrated in the hydrogenation of imines, the catalyst was recycled up to 10 times without either loss of activity or palladium leaching.

The synthesis of highly active and reusable mesoporous siliceous phosphotungstic acid materials (mPTA-Si) which are prepared through a simple self-assembly between phosphotungstic acid (PTA), the polymeric surfactant, and the silica precursor assisted by KCl for cyclohexylation of phenol is reported. The surface area and the acidity of these materials are tuned with a simple adjustment of PTA in the silica framework. The prepared samples exhibit mesoporous structure with a high surface area, but the structure is collapsed when the loading of PTA is high. It is established that the Keggin structure of PTA is retained on the final mPTA-Si. mPTA-Si with different loadings of PTA are employed as the catalysts for the cyclohexylation of phenol under liquid phase conditions. Among the catalysts studied, 10.0-mPTA-8.3Si calcined at 350 degrees C is found to be highly active, selective, and recyclable and offers 100% conversion of phenol with the highest selectivity for p-cyclohexylphenol (96.8%). Refereed/Peer-reviewed

Inexpensive NiXMg2AlOY nanocomposites with high Ni content (Ni wt% > 40%) are developed as efficient catalysts for the sustainable hydrogen production from a mixture of ethanol and water at low temperature. The NiXMg2AlOY nanocomposites are composed of small and uniform nanoparticles (4–6 nm) of NiO, Ni–Mg–(Al)–O and/or MgO. The strong interactions existing between Ni2+ cations and Mg2+ and/or Al3+ cations either in the Ni–Mg–(Al)–O solid solution and/or at the interface of nanoparticles of NiO and/or Ni–Mg–(Al)−O make the catalyst highly active and stable. The behavior of the solids is analyzed in the presence of low and high concentrations of ethanol while maintaining a H2O/EtOH molar ratio of 3. The NiXMg2AlOY catalysts are shown to be efficient toward H2 production between 250 and 650 °C. In the presence of low concentration of ethanol, on the highly loaded Ni compound (Ni12Mg2AlOY), total conversion of ethanol is obtained at 250 °C without formation of CO and carbon, and at 300 °C a H2 yield of 3 mol molEtOH−1 is obtained without the formation of CO, exhibiting a remarkable stability with the time on stream even if some carbon is formed. In high concentration of ethanol, total conversion of ethanol is obtained at 450 °C on the highly loaded Ni compound (Ni12Mg2AlOY). In such conditions, a stable co-generation of carbon nanofibrous materials which amount increases with Ni content is also obtained. The catalytic stability is related to the type and morphology of the carbon species formed. The correlations among the catalyst properties, the catalytic performances and the characterizations are thoroughly discussed.

Several molybdenum(VI) dioxo complexes have been investigated as catalyst precursors for allylic alcohol epoxidation using mainly hydrogen peroxide as oxidant. All catalysts proved to be efficient and selective for the epoxidation of allylic alcohols provided the olefins were rather electron rich. Indeed, electron poor substrates could be converted selectively into the corresponding unsaturated aldehydes. A chiral dioxomolybdenum complex based on an optically pure tridentate Schiff base ligand was synthesized and characterized. Though that complex provided an efficient epoxidation catalyst for allylic alcohols and olefins, no chiral induction was observed. During the X-ray diffraction analysis, the cooling at 100 K led to the appearance of super-lattice reflections on diffraction patterns reflecting an ordering of the structure. Instead of one organometallic species observed at 298 K, three similar complexes of the same molecular structure could be observed in the asymmetric unit at 100 K.

Supported gold catalysts on γ-Al2O3 have been investigated in the catalytic reduction of NO x in simulated Diesel exhaust gas conditions. Different parameters have been examined essentially the mode of gold incorporation via classical deposition–precipitation and anionic exchange methods and the nature of the pre-activation thermal treatment. The resistance to thermal ageing under reactive conditions at 500 °C was found completely different with a significant rate enhancement on anionic-exchange samples. Further comparisons also show that the nature of the pre-activation thermal treatment influences the extent of surface reconstructions during thermal ageing with a detrimental effect of reductive pre-treatment on the catalytic performances.

The real and imaginary parts of third order nonlinear optical susceptibilities (chi((3))) of 10(-4) M solutions of [{Fe-2(CO)(6)}(mu(3)-Y3P){CpCr(CO)(2)}] (Y = S (1) or Se (2)) and the well known precursor clusters [Fe-3(CO)(9)(mu(3)-Y)(2)] (Y = S (3) or Se ( 4)) in toluene were measured using Z-scan and ARINS techniques respectively. Compounds 1 and 2 possess nearly three times the gamma(R) values of their corresponding precursor compounds, 3 and 4. The results suggest a rich potential of mixed-metal, mixed-nonmetal class of clusters as materials exhibiting large nonlinearity.

The propargyl alcohol derivatives (CO) 6 Fe 2 {μ-EC(H)=C(CH 2 OH)E′} (E = Se or Te; E′ = S, Se or Te) were obtained from the room-temperature reaction of Fe 2 (CO) 6 (μ-EE′) with propagyl alcohol and were characterized by IR and 1H , 13 C, 77 Se and 125 Te NMR spectroscopy. The structure of PPh 3 -substituted derivative (CO) 5 (PPh 3 )Fe 2 {μ-SeC(CH 2 OH)=C(H)Se} was established by a single-crystal X-ray diffraction study.

From the room-temperature reaction of the mixed-chalcogenide compound Fe-2(CO)(6)(mu-SeTe) with phenylacetylene two isomeric products were isolated, Fe-2(CO)(6){mu SeC(H)=C-(Ph)Te} (1) and Fe-2(CO)6{mu-SeC(Ph)=C(H)Te} (2). Fe-2(CO)(6)(mu-SSe) reacted with phenylacetylene to form Fe-2(CO)(6){mu-SC(Ph)=C(H)Se} (3). The room-temperature reaction of Fe-2(CO)(6)(mu-STe) with phenylacetylene also yielded two isomeric products, Fe-2(CO)(6)(mu-SC-(H)=C(Ph)Te) (4) and Fe-2(CO)(6)(mu-SC(Ph)=C(H)Te) (5). In ah of these reactions, the homochalcogenide compounds Fe-2(CO)(6)(mu-EC(H)=C(Ph)E) (E = Se, Te, E = S, Se, and E = S, Te, respectively) were also formed in trace amounts. The new compounds 1-5 were characterized by IR and H-1, C-13, Se-77, and Te-125 NMR spectroscopy. Compound 1 was structurally characterized by single-crystal X-ray diffraction methods. It crystallized in the triclinic space group P $($) over bar$$ 1 with a = 7.773(9) Angstrom, b = 10.635(9) Angstrom, c = 12.010(10) Angstrom, a = 104.99(10)degrees, beta = 102.86(11)degrees, gamma = 106.38(9)degrees, V = 872.1(8) Angstrom(3), Z = 2, and D(calc) = 2.241 g cm(-3).Full-matrix least-squares refinement of 1 converged to R = 0.077 and R(w) = 0.086.