Spectroscopic Properties,Conformation and Structure of Difluorothiophosphoryl Isocyanate in the Gaseous and Solid Phase

Difluorothiophosphoryl isocyanate, F₂P(S)NCO was characterized with UV/vis, NMR, IR (gas and Ar-matrix), and Raman (liquid) spectroscopy. Its molecular structure was also established by means of gas electron diffraction (GED) and single crystal X-ray diffraction (XRD) in the gas phase and solid state, respectively. The analysis of the spectroscopic data and molecular structures is complemented by extensive quantum-chemical calculations. Theoretically, the C_s symmetric syn-conformer is predicted to be the most stable conformation. Rotation about the P−N bond requires about 9 kJ mol⁻¹ and the predicted existence of an anti-conformer is dependent on the quantum-chemical method used. This syn-orientation of the isocyanate group is the only one found in the gas phase and contained likewise in the crystal. The overall molecular structure is very similar in gas and solid, despite in the solid state the molecules arrange through intramolecular O⋅⋅⋅F contacts into layers, which are further interconnected by S⋅⋅⋅N, S⋅⋅⋅C and C⋅⋅⋅F contacts. Additionally, the photodecomposition of F₂P(S)NCO to form CO, F₂P(S)N, and F₂PNCO is observed in the solid Ar-matrix.     

One‐Pot Cooperation of Single‐Atom Rh and Ru Solid Catalysts for a Selective Tandem Olefin Isomerization‐Hydrosilylation Process

Realizing the full potential of oxide‐supported single‐atom metal catalysts (SACs) is key to successfully bridge the gap between the fields of homogeneous and heterogeneous catalysis. Here we show that the one‐pot combination of Ru₁/CeO₂ and Rh₁/CeO₂ SACs enables a highly selective olefin isomerization‐hydrosilylation tandem process, hitherto restricted to molecular catalysts in solution. Individually, monoatomic Ru and Rh sites show a remarkable reaction specificity for olefin double‐bond migration and anti‐Markovnikov α‐olefin hydrosilylation, respectively. First‐principles DFT calculations ascribe such selectivity to differences in the binding strength of the olefin substrate to the monoatomic metal centers. The single‐pot cooperation of the two SACs allows the production of terminal organosilane compounds with high regio‐selectivity (>95 %) even from industrially‐relevant complex mixtures of terminal and internal olefins, alongside a straightforward catalyst recycling and reuse. These results demonstrate the significance of oxide‐supported single‐atom metal catalysts in tandem catalytic reactions, which are central for the intensification of chemical processes.     

Reaction behaviour of monomeric β-ketoesters, 4. Polymer network formation by Michael reaction of multifunctional acetoacetates with multifunctional acrylates

Based on the Michael reaction of multifunctional acetoacetates with multiacrylates, in the presence or absence of dimethacrylates, tailor made matrix materials can be prepared. This can be achieved in a one- or two-step process. The Michael addition (first step) can be followed by radiation curing of excessive acrylate (second step).     

Some remarks on multilinear exponential sums with an application

A sum-product equation is considered in prime fields. We bound a multilinear exponential sum with an additional requirement for some sets.     

Limiting the Number of Potential Binding Modes by Introducing Symmetry into Ligands: Structure‐Based Design of Inhibitors for Trypsin‐Like Serine Proteases

In the absence of X‐ray data, the exploration of compound binding modes continues to be a challenging task. For structure‐based design, specific features of active sites in different targets play a major role in rationalizing ligand binding characteristics. For example, dibasic compounds have been reported as potent inhibitors of various trypsin‐like serine proteases, the active sites of which contain several binding pockets that can be targeted by cationic moieties. This results in several possible orientations within the active site, complicating the binding mode prediction of such compounds by docking tools. Therefore, we introduced symmetry in bi‐ and tribasic compounds to reduce conformational space in docking calculations and to simplify binding mode selection by limiting the number of possible pocket occupations. Asymmetric bisbenzamidines were used as starting points for a multistage and structure‐guided optimization. A series of 24 final compounds with either two or three benzamidine substructures was ultimately synthesized and evaluated as inhibitors of five serine proteases, leading to potent symmetric inhibitors for the pharmaceutical drug targets matriptase, matriptase‐2, thrombin and factor Xa. This study underlines the relevance of ligand symmetry for chemical biology.