Visible and NIR Light Assistance of the N2 Reduction to NH3 Catalyzed by Cs-promoted Ru Nanoparticles Supported on Strontium Titanate

NH₃ production accounts for more than 1% of the total CO₂ emissions and is considered one of the most energy-intensive industrial processes currently (T > 400 °C and P > 80 bars). The development of atmospheric-pressure N₂ fixation to NH₃ under mild conditions is attracting much attention, especially using additional renewable energy sources. Herein, efficient photothermal NH₃ evolution in continuous flow upon visible and NIR light irradiation at near 1 Sun power using Cs-decorated strontium titanate-supported Ru nanoparticles is reported. Notably, for the optimal photocatalytic composition, a constant NH₃ rate near 3500 μmol_NH3 g_catalyst^–1 h^–1 was achieved for 120 h reactions, being among the highest values reported at atmospheric pressure under 1 Sun irradiation.

Homogeneous catalysis with polyhydride complexes

This review analyzes the role of transition metal polyhydrides as homogeneous catalysts for organic reactions. Discussed reactions involve nearly every main organic functional group.

From the discovery of field ionization to field desorption and liquid injection field desorption/ionization-mass spectrometry-A journey from principles and applications to a glimpse into the future

The discovery of the ionizing effect of strong electric fields in the order of volts per Ångstrom in the early 1950s eventually led to the development of field ionization-mass spectrometry (FI-MS). Due to the very low ion currents, and thus, limited by the instrumentation of the 1960s, it took some time for the, by then, new technique to become adopted for analytical applications. In FI-MS, volatile or at least vaporizable samples mainly deliver molecular ions, and consequently, mass spectra showing no or at least minor numbers of fragment ion signals. The next major breakthrough was achieved by overcoming the need to evaporate the analyte prior to ionization. This was accomplished in the early 1970s by simply depositing the samples onto the field emitter and led to field desorption-mass spectrometry (FD-MS). With FD-MS, a desorption ionization method had become available that paved the road to the mass spectral analysis of larger molecules of low to high polarity and even of organic salts. In FD-MS, all of these analytes deliver spectra with no or at least few fragment ion peaks. The last milestone was the development of liquid injection field desorption/ionization (LIFDI) in the early 2000s that allows for sample deposition under the exclusion of atmospheric oxygen and water. In addition to sampling under inert conditions, LIFDI also enables more robust and quicker operation than classical FI-MS and FD-MS procedures. The development and applications of FI, FD, and LIFDI had mutual interference with the mass analyzers that were used in combination with these methods. Vice versa, the demand for using these techniques on other than magnetic sector instruments has effectuated their adaptation to different types of modern mass analyzers. The journey started with magnetic sector instruments, almost skipped quadrupole analyzers, encompassed Fourier transform ion cyclotron resonance (FT-ICR) and orthogonal acceleration time-of-flight (oaTOF) analyzers, and finally arrived at Orbitraps. Even interfaces for continuous-flow LIFDI have been realized. Even though being niche techniques to some degree, one may be confident that FI, FD, and LIFDI have a promising future ahead of them. This Account takes you on the journey from principles and applications of the title methods to a glimpse into the future.

Amide versus amine ligand paradigm in the direct amination of alcohols with Ru-PNP complexes

Ruthenium complexes of PNP-ligands bearing secondary amines were found to be inactive in the alcohol amination with NH₃, while all complexes of homologous ligands bearing tertiary amines gave active catalysts!

β-Aminocarbonates in Regioselective and Ring Expansion Reactions

The reactivity of β-aminocarbonates as anisotropic electrophiles has been investigated with several phenols. Products distribution shows that the regioselectivity of the anchimerically driven alkylation reaction depends on the nucleophiles. The results suggest that in the presence of nucleophiles that are also good leaving groups, the reaction takes place under thermodynamic control favoring the attack on the most sterically hindered carbon of the cyclic aziridinium intermediate. Furthermore, when an enantiomerically pure pyrrolidine-based carbonate was used, the reaction with phenols proceeds via a bicyclic aziridinium intermediate leading to the stereoselective synthesis of optically active 3-substituted piperidines via ring expansion reaction. These results were confirmed both by NMR spectroscopy and X-ray diffraction analysis.

(BB)-Carboryne Complex of Ruthenium: Synthesis by Double B-H Activation at a Single Metal Center

The first example of a transition metal (BB)-carboryne complex containing two boron atoms of the icosahedral cage connected to a single exohedral metal center (POBBOP)Ru(CO)2 (POBBOP = 1,7-OP(i-Pr)2-2,6-dehydro-m-carborane) was synthesized by double B-H activation within the strained m-carboranyl pincer framework. Theoretical calculations revealed that the unique three-membered (BB)>Ru metalacycle is formed by two bent B-Ru σ-bonds with the concomitant increase of the bond order between the two metalated boron atoms. The reactivity of the highly strained electron-rich (BB)-carboryne fragment with small molecules was probed by reactions with electrophiles. The carboryne-carboranyl transformations reported herein represent a new mode of cooperative metal-ligand reactivity of boron-based complexes.

Synthesis and catalytic performance of ruthenium complexes ligated with rigid o-(diphenylphosphino)aniline for chemoselective hydrogenation of dimethyl oxalate

New ruthenium complexes with rigid ligand o-(diphenylphosphino)aniline exhibit excellent performance in chemoselective hydrogenation of dimethyl oxalate to methyl glycolate.

Selective conversion of alcohols in water to carboxylic acids by in situ generated ruthenium trans dihydrido carbonyl PNP complexes

In this work, we present a mild method for direct conversion of primary alcohols into carboxylic acids with the use of water as an oxygen source.