A mechanistic investigation into the guanidine catalyzed reductive amination of CO 2 , using a combination of 1 H, 29 Si NMR, FT-IR, MS and GC profiling, is reported. Inexpensive and readily available N N N N-tetramethylguanidine (TMG) was found to be an equally effective catalyst compared to more elaborate cyclic guanidines. Different catalytic pathways to formamide 2, aminal 4 and N-methylamine 3, were identified. A pathway to formamide product 2 dominates at 23 °C. Increasing the reaction temperature to 60 °C enables a competitive, higher energy pathway to 4 and 3, which requires direct reduction of CO 2 with PhSiH 3 to formoxysilane E. Reduction of aminal 4, in the presence of CO 2 and the catalyst, led to formation of a 1 : 1 ratio of 2 and 3. The catalyst itself can be formylated under the reaction conditions, resulting in its deactivation. Thus, alkylated TMGs were found to be more stable and more active catalysts than TMG, leading to a successful organocatalyzed reductive functionalization of CO 2 with silane at 0.1 mol% catalyst loading (TON = 805 and TOF = 33.5 h-1).

The first observation of guanidine–CO2 ‘activation’ complexes in solution and their implications on the catalytic activity of guanidines are reported.

Synopsis:The performance of the XMaS beamline for soft X-ray spectroscopy in the 2-4 keV range is assessed with particular relation to in situ studies of functional materials and their chemistry. X-ray spectroscopy for chemistry in the 2-4 keV energy regime at the XMaS beamline: ionic liquids, Rh and Pd catalysts in gas and liquid environments, and Cl contamination in c-Al 2 O 3 How to cite your article in pressYour article has not yet been assigned page numbers, but may be cited using the doi:Thompson, P.B.J., Nguyen, B.N., Nicholls, R., Bourne, R.A., Brazier, J.B., Lovelock, K.R.J., Brown, S.D., Wermeille, D., Bikondoa, O., Lucas, C.A. et al. (2015). J. Synchrotron Rad. 22, doi:10.1107/S1600577515016148.You will be sent the full citation when your article is published and also given instructions on how to download an electronic reprint of your article. Proof instructionsProof corrections should be returned by 22 September 2015. After this period, the Editors reserve the right to publish your article with only the Managing Editor's corrections. Please(1) Read these proofs and assess whether any corrections are necessary.(2) Check that any technical editing queries highlighted in bold underlined text have been answered. (3) Send corrections by e-mail to tw@iucr.org. Please describe corrections using plain text, where possible, giving the line numbers indicated in the proof. Please do not make corrections to the pdf file electronically and please do not return the pdf file. If no corrections are required please let us know.If you wish to make your article open access or purchase printed offprints, please complete the attached order form and return it by e-mail as soon as possible. Thumbnail image for contents pageFiles: s/rv5038/rv5038.3d s/rv5038/rv5038.sgml RV5038 FA IU-1517/10(15)9 1516/52(15)9 () RV5038 http://dx.doi.org/10.1107/S1600577515016148 1 of 14 The 2-4 keV energy range provides a rich window into many facets of materials science and chemistry. Within this window, P, S, Cl, K and Ca K-edges may be found along with the L-edges of industrially important elements from Y through to Sn. Yet, relative to those that cater for energies above ca. 4-5 keV, there are relatively few resources available for X-ray spectroscopy below these energies. In addition, in situ or operando studies become to varying degrees more challenging than at higher X-ray energies due to restrictions imposed by the lower energies of the X-rays upon the design and construction of appropriate sample environments. The XMaS beamline at the ESRF has recently made efforts to extend its operational energy range to include this softer end of the X-ray spectrum. In this report the resulting performance of this resource for X-ray spectroscopy is detailed with specific attention drawn to: understanding electrostatic and charge transfer effects at the S K-edge in ionic liquids; quantification of dilution limits at the Cl K-and Rh L 3 -edges and structural equilibria in solution; in vacuum deposition and reduction of [Rh I (CO) 2 Cl] 2 to -Al 2 ...

This paper describes the application of Raman spectroscopy to whole hair fibers. Previously this has proved difficult because the hairs are relatively opaque, and spatial resolution diminishes with depth because of the change in refractive index. A solution is to couple confocal Raman with multivariate curve resolution (MCR) data analysis, which separates spectral differences with depth despite this reduction in resolution. Initially, it is shown that the cuticle can be separated from the cortex, showing the differences in the proteins, which can then be plotted as a function of depth, with the cuticle factor being seen only at the surface as expected. Hairs that had been treated in different ways, e.g., by bleaching, treatment with the active molecule resorcinol followed by rinsing and treatment with a full hair care product, were also examined. In all cases, changes to the hair are identified and are associated with specific parts of the fiber. Since the hair fiber is kept intact, it can be repeatedly treated and measured, hence multistep treatment processes can be followed. This method expands the potential use of Raman spectroscopy in hair research.

The chemical composition and the electronic state of the surface of alloys or mixed oxides with enhanced electrocatalytic properties are usually heterogeneous at the nanoscale. The non-uniform distribution of the potential across their surface affects both activity and stability. Studying such heterogeneities at the relevant length scale is crucial for understanding the relationships between structure and catalytic behaviour. Here, we demonstrate an experimental approach combining scanning photoemission electron microscopy and atom probe tomography performed at identical locations to characterise the surface's structure and oxidation states, and the chemical composition of the surface and sub-surface regions. Showcased on an Ir-Ru thermally grown oxide, an efficient catalyst for the anodic oxygen evolution reaction, the complementary techniques yield consistent results in terms of the determined surface oxidation states and local oxide stoichiometry. Significant chemical heterogeneities in the sputter-deposited Ir-Ru alloy thin films govern the oxide's chemistry, observed after thermal oxidation both laterally and vertically. While the oxide grains have a composition of Ir 0.94 Ru 0.06 O 2 , the composition in the grain boundary region varies from Ir 0.70 Ru 0.30 O 2 to Ir 0.40 Ru 0.60 O 2 and eventually to Ir 0.75 Ru 0.25 O 2 from the top surface into the depth. The influence of such compositional non-uniformities on the catalytic performance of the material is discussed, along with possible engineering levers for the synthesis of more stable and reactive mixed oxides. The proposed method provides a framework for investigating materials of interest in the field of electrocatalysis and beyond.

Single-atom alloys (SAAs) have recently gained considerable attention in the field of heterogeneous catalysis research due to their potential for novel catalytic properties. While SAAs are often examined in reactions of reductive atmospheres, such as hydrogenation reactions, in the present work, we change the focus to AgPd SAAs in oxidative environments since Pd has the highest catalytic activity of all metals for oxidative reactions. Here, we examine how the chemical reactivity of AgPd SAAs differs from its constituent Pd in an oxidative atmosphere. For this purpose, electronic structure changes in an Ag0.98Pd0.02 SAA foil in 1 mbar of O2 were studied by in situ x-ray photoemission spectroscopy and compared with the electronic structure of a Pd foil under the same conditions. When heated in an oxidative atmosphere, Pd in Ag0.98Pd0.02 partly oxidizes and forms a metastable PdOx surface oxide. By using a peak area modeling procedure, we conclude that PdOx on Ag0.98Pd0.02 is present as thin, possibly monolayer thick, PdOx islands on the surface. In comparison to the PdO formed on the Pd foil, the PdOx formed on AgPd is substantially less thermodynamically stable, decomposing at temperatures about 270 °C lower than the native oxide on Pd. Such behavior is an interesting property of oxides formed on dilute alloys, which could be potentially utilized in catalytic oxidative reactions such as methane oxidation.

In situ X-ray absorption spectroscopy (XAS) and Pd K, L III , and Cl K-edges shows that Cl can be present in significant amounts in ENCAT™ 30 catalysts and that it can severely retard Pd nanoparticle (NP) development in flowing solvents. We also show that whilst polymeric encapsulation protects the Pd against solvent induced agglomeration of Pd nanoparticles the evidence suggests it does not prevent the formation PdH x through reaction with the aqeous ethanol solvent, and that, as received, ENCAT™ 30 NP catalysts are not, for the most part, comprised of nanoparticulate Pd 0 irrespective of the presence of Cl.

Funding informationMax-Planck-Gesellschaft X-ray photoemission spectroscopy (XPS) measurements in near-ambient pressure (NAP) conditions result in a signal loss of the primary spectrum as a result of inelastic scattering of photoelectrons in the gas phase. The inelastic scattering of the primary