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Sasol Ltd., the University of Glasgow and the EPSRC (grant numbers EP/P504937/1 and EP/P505534/1) are thanked for the provision of postgraduate studentships (RW and ALD). The STFC Rutherford Appleton Laboratory is thanked for access to neutron beam facilities. The Royal Society is thanked for the provision of an Industrial Fellowship (PBW). Fischer-Tropsch synthesis (FTS) is commonly viewed as an alternative approach to the production of diesel fuels via sources independent of crude oil. The adaptability of the FTS process allows for the selective production of shorter chain C2 to C6 hydrocarbons and has the potential to be a legitimate source of useable chemical feedstocks with high value to the chemical manufacturing industry. Interestingly, although recognised as a poison in most catalytic systems, small amounts of sulfur in iron-based FTS catalysts has been demonstrated to promote catalyst reducibility and activity towards shorter chain hydrocarbons. However, it is not known what impact sulfur has on the formation of hydrocarbonaceous surface species that have been proposed to play a pivotal role in the mediation of reactants during iron FTS. Here we apply ambient pressure CO hydrogenation at 623 K on a selection of sulfur promoted iron FTS catalysts to investigate the effect of sulfur content on hydrocarbonaceous species formation. For the first time, we report the application of inelastic neutron scattering to quantify the presence of hydrocarbonaceous species under the presence of sulfur promotion. In combination with temperature programmed oxidation, X-ray diffraction, and Raman spectroscopy, we observe how low sulfur loadings (

The ready construction of 24 stereochemically and functionally diverse carbohydrate ligand structures from a core D-glucosamine scaffold has allowed the evaluation of broad ranging structure activity relationships in ligand accelerated zincate additions to aldehydes, with variations in deltadeltaG+/+(R-S) of up to 5650 J mol(-1) that create opposing senses of asymmetric induction and that are consistent with models based on several ligand X-ray structures and molecular mechanics analysis. Factorial analysis of enantioselectivity using key dihedral angles and steric volume on N-2 also highlight the potential for the use of factorial design in ligand construction.

The electrocatalytic reduction of CO2 at carbon-supported Au-Pd core–shell nanoparticles is investigated systematically as a function of the Pd shell thickness. Liquid- and gas-phase products were determined by off-line 1H NMR spectroscopy and on-line electrochemical mass spectrometry. Our results uncover the relationship between the nature of the products generated and the Pd shell thickness. CO and H2 are the only products generated at 1 nm thick shells, whereas shells of 5 and 10 nm produced HCOO−, CH4 and C2H6. The concentration of HCOO− detected in the electrolyte was dependent on the applied potential and reached a maximum Faradaic efficiency of 27 % at −0.5 V versus the reversible hydrogen electrode for 10 nm thick shells. We conclude that collisions between absorbed hydrogen at relaxed Pd lattices and strongly bound “CO-like” intermediates promote the complete hydrogenation to C1 and C2 alkanes without the generation of other products, such as alcohols and aldehydes.

We report a facile biomimetic sol-gel synthesis using the sponge phase formed by the lipid monoolein as a structure-directing template, resulting in high phase purity, mesoporous dysprosium- and gadolinium titanates. The stability of monoolein in a 1,4-butanediol and water mixture complements the use of a simple sol-gel metal oxide synthesis route. By judicious control of the lipid/solvent concentration, the sponge phase of monoolein can be directly realised in the pyrochlore material, leading to a porous metal oxide network with an average pore diameter of 10 nm.

The reactivity of a series of organometallic rare earth and actinide complexes with hemilabile NHC-ligands towards substrates with acidic C-H and N-H bonds is described. The synthesis, characterisation and X-ray structures of the new heteroleptic mono- and bis(NHC) cyclopentadienyl complexes LnCp2(L) 1 (Ln = Sc, Y, Ce; L = alkoxy-tethered carbene [OCMe2CH2(1-C{NCHCHNiPr})]), LnCp(L)2 (Ln = Y) 2, and the homoleptic tetrakis(NHC) complex Th(L)4 4 are described. The reactivity of these complexes, and of the homoleptic complexes Ln(L)3 (Ln = Sc 3, Ce), with E-H substrates is described, where EH = pyrrole C4H4NH, indole C8H6NH, diphenylacetone Ph2CC(O)Me, terminal alkynes RC[triple bond, length as m-dash]CH (R = Me3Si, Ph), and cyclopentadiene C5H6. Complex 1-Y heterolytically cleaves and adds pyrrole and indole N-H across the metal carbene bond, whereas 1-Ce does not, although 3 and 4 form H-bonded adducts. Complexes 1-Y and 1-Sc form adducts with CpH without cleaving the acidic C-H bond, 1-Ce cleaves the Cp-H bond, but 2 reacts to form the very rare H+-[C5H5]--H+ motif. Complex 1-Ce cleaves alkyne C-H bonds but the products rearrange upon formation, while complex 1-Y cleaves the C-H bond in diphenylacetone forming a product which rearranges to the Y-O bonded enolate product.

Fe/SiO2 and Rh-Fe/SiO2 catalysts with increasing Fe/Rh ratio have been prepared and characterized by TEM, XRD, oxygen adsorption and Mossbauer spectroscopy. It was confirmed that Fe/SiO2 catalysts cannot be reduced under hydrogen flow, to more than 50 % whatever the temperature in the 200-500 A degrees C range and shown that the presence of even a small amount of Rh (Fe/Rh a parts per thousand currency sign2,000) promoted the reduction of iron up to 85-95 %. This promoting effect also took place with a Fe/SiO2 + Rh/SiO2 physical mixture (Fe/Rh a parts per thousand currency sign2,000). Therefore, the occurrence of a hydrogen spillover effect may be involved in the observed process.

Two functional groups can be delivered at once to organo-rare earth complexes, (L)MR(2) and (L)(2)MR (M = Sc, Y; L = ({1-C(NDippCH(2)CH(2)N)}CH(2)CMe(2)O), Dipp = 2,6-(i)Pr(2)-C(6)H(3); R = CH(2)SiMe(3), CH(2)CMe(3)), via the addition of E-X across the metal-carbene bond to form a zwitterionic imidazolinium-metal complex, (L(E))MR(2)X, where L(E) = {1-EC(NDippCH(2)CH(2)N)}CH(2)CMe(2)O, E is a p-block functional group such as SiR(3), PR(2), or SnR(3), and X is a halide. The "ate" complex (L(Li))ScR(3) is readily accessible and is best described as a Li carbene adduct, ({1-Li(THF)C(NDippCH(2)CH(2)N)}CH(2)CMe(2)O)Sc(CH(2)SiMe(3))(3), since structural characterization shows the alkoxide ligand bridging the two metals and the carbene Li-bound with the shortest yet recorded Li-C bond distance. This can be converted via lithium halide-eliminating salt metathesis reactions to alkylated or silylated imidazolinium derivatives, (L(E))ScR(3) (E = SiMe(3) or CPh(3)). All the E-functionalized imidazolinium complexes spontaneously eliminate functionalized hydrocarbyl compounds upon warming to room temperature or slightly above, forming new organic products ER, i.e., forming C-Si, C-P, and C-Sn bonds, and re-forming the inorganic metal carbene (L)MR(X) or (L)(2)MX complex, respectively. Warming the tris(alkyl) complexes (L(E))MR(3) forms organic products arising from C-C or C-Si bond formation, which appears to proceed via the same elimination route. Treatment of (L)(2)Sc(CH(2)SiMe(3)) with iodopentafluorobenzene results in the "reverse sense" addition, which upon thermolysis forms the metal aryl complex (L)(2)Sc(C(6)F(5)) and releases the iodoalkane Me(3)SiCH(2)I, again facilitated by the reversible functionalization of the N-heterocyclic carbene group in these tethered systems.

Silyl, phosphinyl, stannyl, and boryl reagents can be added across the neutral metal-carbon dative bond in d0 f-block metal N-heterocyclic carbene complexes in a reversible manner, allowing additional functional groups to be incorporated into redox-inactive organo-f-block compounds.

International audience; The new ambiphilic ligand Ph2P–(1,1′-ferrocenyl)–BMes2, prepared by sequential lithiation/electrophilic trapping of 1,1′-dibromoferrocene, adopts a monomeric structure free of dative P → B and Fe → B interactions. This flexible phosphine-borane and the related o-phenylene bridged system have been evaluated in Rh-catalyzed hydroformylation.