The ethenolysis of cardanol (2), a waste product from cashew kernel production, was carried out using a variety of metathesis catalysts. Surprisingly, the best activities and selectivities could be observed with ruthenium based 1st generation type catalysts converting cardanol (2) almost completely to the corresponding 1-octene (6) and 3-non-8-enylphenol (4), a potential detergent precursor. Detailed investigation of the reaction system showed that the high activity and selectivity were due to a combination of ethenolysis and internal self-metathesis of the unsaturated cardanol mixture, 2. Self-metathesis of cardanol (2) containing three double bonds led to the formation of 3-non-8-enylphenol (4) and 1,4-cyclohexadiene (7). The latter was crucial for a high selectivity and activity in the ethenolysis, not only of cardanol (2), but also of other substrates like methyl oleate (10) when using ruthenium based 1st generation catalysts. The endocrine disrupting properties of 3-nonylphenol and related compounds are compared

Homogeneous chromium catalysts for the selective conversion of ethene to hex-1-ene are formed from Cr(III) reagents, aminothioether ligands of the type HN-(CH 2 CH 2 SR) 2 , and aluminum reagents. In this study, the early activation steps are investigated by EPR, UV−visible, and Cr K-edge XAFS spectroscopy; rapid stopped-flow mixing and a freeze-quench allows good quality EXAFS analysis of a species formed in ∼1 s of reaction. This is shown to involve reduction to Cr(II) and deprotonation of a NH group of the auxiliary ligand. This 4-coordinate metal center may act as precursor for the coordination of ethene and subsequent selective oligomerization.

The rational design of low-cost transition metal catalysts that exhibit high activity and selectivity may be the most significantly investigated in heterogeneous catalysis. In this study, Co 3-x Mn x O 4 (x = 0.75, 1.0, and 1.5) mixed metal oxides were successfully synthesized by a controlled template-free autoclave strategy and studied for toluene oxidation. It is found that the Co-rich sample showed markedly enhanced activity and the 3D dandelion-like Co 2.25 Mn 0.75 O 4 catalyst exhibited in the highest toluene oxidation rate (8.9 mmol/(g cat s)) and a 100 % toluene conversion at 239 8C. In situ DRIFTS study indicates that toluene was sequentially oxidized to benzyl radical, benzaldehyde, benzene, oxalic acid, and finally to CO 2 and H 2 O. The interaction between Co and Mn, in conjunction with the high concentration of surface oxygen species and rich surface oxygen vacancies, reasonably explains the elevated catalytic activity and thermal stability for toluene oxidation over 3D flower-like Co 3-x Mn x O 4 spinel catalysts.

(2008) Probing the effects of ligand structure on activity and selectivity of Cr(III) complexes for ethylene oligomerisation and polymerization, Dalton Transactions, 1177-1185. (DOI: 10.1039 Stuart A. Bartlett, Giannantonio Cibin, Andrew J. Dent, John Evans, Martin J. Hanton, Gillian Reid, Robert P. Tooze, and Moniek Tromp, (2013) Sc(III) complexes with neutral N3-and SNS-donor ligands -a spectroscopic study of the activation of ethene polymerisation catalysts. Dalton Transactions, 42, (6), 2213Transactions, 42, (6), -2223Transactions, 42, (6), . (doi:10.1039 • Time-resolved and newly developed freeze-quench stopped flow XAS studies.• Stepwise displacement of halide observed, forming [Mo(CH 3 ) 3 (L)], without Mo dimers.• Reaction kinetics depending on metal and halide.• Decomposition of activated species to Mo precipitate. solutions within 1 second of mixing, opens up a large field of homogeneous catalysis and liquid chemistry to be studied, being able to quench at sub second time scales, while characterisation techniques with long data acquisition can be performed.

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Core/shell nanocrystals with a graded interface between core and shell exhibit improved optoelectronic properties compared with particles with an abrupt, sharp interface. Material gradients mitigate interfacial defects and define the shape of the confinement potential. So far, few works exist that allow to quantify the width of the gradient. In this study, ZnSe/CdS nanocrystals with graded shells made at different temperatures are characterized using extended X-ray absorption fine structure (EXAFS) and Raman spectroscopies. The average coordination number of the probed element with respect to the two possible counterions is fit to a simple, geometric model. It is shown that at the lower temperature limit for shell growth (260 °C), substantial interfacial alloying can be attributed mainly to cation migration. At higher temperature (290 °C), strain minimization leads to atomic ordering of the metal ions and an anomalously low degree of phase mixing.

Complexes with weakly coordinating ligands are often formed in chemical reactions and can play key roles in determining the reactivity, particularly in catalytic reactions. Using time-resolved X-ray absorption fine structure (XAFS) spectroscopy in combination with time-resolved IR (TRIR) spectroscopy and tungsten hexacarbonyl, W­(CO)6, we are able to structurally characterize the formation of an organometallic alkane complex, determine the W–C distances, and monitor the reactivity with silane to form an organometallic silane complex. Experiments in perfluorosolvents doped with xenon afford initially the corresponding solvated complex, which is sufficiently reactive in the presence of Xe that we can then observe the coordination of Xe to the metal center, providing a unique insight into the metal–xenon bonding. These results offer a step toward elucidating the structure, bonding, and chemical reactivity of transient species by X-ray absorption spectroscopy, which has sensitivity to small structural changes. The XAFS results indicate that the bond lengths of metal–alkane (W–H–C) bond in W­(CO)5(heptane) as 3.07 (±0.06) Å, which is longer than the calculated W–C (2.86 Å) for binding of the primary C–H, but shorter than the calculated W–C (3.12 Å) for the secondary C–H. A statistical average of the calculated W–C alkane bond lengths is 3.02 Å, and comparison of this value indicates that the value derived from the XAFS measurements is averaged over coordination of all C–H bonds consistent with alkane chain walking. Photolysis of W­(CO)6 in the presence of HSiBu3 allows the conversion of W­(CO)5(heptane) to W­(CO)5(HSiBu3) with an estimated W–Si distance of 3.20 (±0.03) Å. Time-resolved TRIR and XAFS experiments following photolysis of W­(CO)6 in perfluoromethylcyclohexane (PFMCH) allows the characterization of W­(CO)5(PFMCH) with a W–F distance of 2.65 (±0.06) Å, and doping PFMCH with Xe allows the characterization of W­(CO)5Xe with a W–Xe bond length of 3.10 (±0.02) Å.

Scandium trichloride complexes with tridentate N(3)- and S(2)N-donor ligands (L(3)) have been synthesised and characterised by IR, (1)H, (13)C{(1)H} and (45)Sc NMR spectroscopy, microanalysis, and solid state and solution XAFS spectroscopy. Catalytic testing of a subset of these complexes with ethene has been undertaken in chlorobenzene with MMAO-3A and PMAO-IP at 60 °C and 40 bar ethene, giving low activity ethene polymerisation. The reactions of these complexes with MeLi and AlMe(3) were studied by (1)H, (13)C{(1)H}, (27)Al and (45)Sc NMR spectroscopy and in situ via Sc K-edge XAFS spectroscopy. Three or four mol. equivalents of MeLi react with [ScCl(3)(Me(3)-tacn)] in THF solution to form [ScMe(3)(Me(3)-tacn)] cleanly, while complexes of type [ScCl(3)(R-SNS)] {R-SNS = HN(CH(2)CH(2)SC(10)H(21))(2)} form two different species proposed to be [ScMe(3)(R-SN(Li)S)] and [ScMe(2)(R-SN(-)S)]. In contrast, in situ(45)Sc NMR and Sc K-edge XAFS spectroscopic studies of the reaction of [ScCl(3)(Me(3)-tacn)] with 10 mol. equivalents of AlMe(3) strongly suggest that alkylation at the Sc(III) centre does not occur, instead retaining the Cl(3)N(3) coordination environment and most likely forming Sc-Cl-AlMe(3) bridging interactions. Similar studies on [ScCl(3)(decyl-SNS)] with 10 mol. equivalents of AlMe(3) are also consistent with this, indicating that alkylation at the Sc centre does not occur except in the presence of co-catalyst [Ph(3)C][Al{OC(CF(3))(3)}(4)] and the α-alkene, hex-1-ene.