Mono- and Bisionic Mo- and W-Based Schrock Catalysts for Biphasic Olefin Metathesis Reactions in Ionic Liquids

Structural insight into piezo-solvatochromism of Reichardt's dye

To date, accurate modelling of the solvation process is challenging, often over-simplifying the solvent-solute interactions. The interplay between the molecular arrangement associated with the solvation process and crystal nucleation has been investigated by analysis of the piezo-solvatochromic behaviour of Reichardt's dye, ET(1), in methanol, ethanol and acetone under high pressure. High-pressure single-crystal X-ray diffraction and UV-Vis spectroscopy reveal the impact of solute-solvent interactions on the optical properties of ET(1). The study underscores the intricate relationship between solvent properties, molecular conformation and crystal packing. The connection between liquid and solid phases emphasizes the capabilities of high-pressure methods for expanding the field of crystal engineering. The high-pressure environment allowed the determination of the crystal structures reported here that are built from organic molecules fourfold solvated with ethanol or methanol: ET(1)·4CH3OH and ET(1)·4C2H5OH·H2O. The observed piezo-solvatochromic effects highlight the potential of ET(1) in nonlinear optoelectronics and expand the application of solvatochromic chemical indicators to pressure sensors.

Ionic Liquids in Metal, Photo-, Electro-, and (Bio) Catalysis

Ionic liquids (ILs) have unique physicochemical properties that make them advantageous for catalysis, such as low vapor pressure, non-flammability, high thermal and chemical stabilities, and the ability to enhance the activity and stability of (bio)catalysts. ILs can improve the efficiency, selectivity, and sustainability of bio(transformations) by acting as activators of enzymes, selectively dissolving substrates and products, and reducing toxicity. They can also be recycled and reused multiple times without losing their effectiveness. ILs based on imidazolium cation are preferred for structural organization aspects, with a semiorganized layer surrounding the catalyst. ILs act as a container, providing a confined space that allows modulation of electronic and geometric effects, miscibility of reactants and products, and residence time of species. ILs can stabilize ionic and radical species and control the catalytic activity of dynamic processes. Supported IL phase (SILP) derivatives and polymeric ILs (PILs) are good options for molecular engineering of greener catalytic processes. The major factors governing metal, photo-, electro-, and biocatalysts in ILs are discussed in detail based on the vast literature available over the past two and a half decades. Catalytic reactions, ranging from hydrogenation and cross-coupling to oxidations, promoted by homogeneous and heterogeneous catalysts in both single and multiphase conditions, are extensively reviewed and discussed considering the knowledge accumulated until now.

Synthesis of trans-Tetrafluoro(trifluoromethyl)-λ6-sulfanyl (CF3SF4)-Containing Olefins via Cross Metathesis

The cross-metathesis reactions of trans-tetrafluoro(trifluoromethyl)-λ⁶-sulfanyl (CF₃SF₄)-containing olefins expand the repertoire of synthetic transformations of CF₃SF₄-substituted molecules. Treatment of a primary alkene and 3-CF₃SF₄-propene with a second-generation Hoveyda-Grubbs catalyst yielded the cross-metathesis product in good yield under very mild conditions (room temperature). CF₃SF₄-propene undergoes cross metathesis with substrates containing electron-withdrawing groups or electron-donating groups at room temperature or under dichloromethane reflux. The formation of the CF₃SF₄-propene homodimer and the utility of that dimer to undergo selective cross-metathesis reactions are described.

cis-Specific ring opening metathesis polymerisation (ROMP) of cyclic olefins using (pentafluorophenylimido)vanadium(v)-alkylidene, V(CHSiMe3)(NC6F5)[OC(CF3)3](PMe3)2

Highly cis-specific (Z selective) ring opening metathesis polymerisation of cycloheptene has been demonstrated using V(CHSiMe₃)(NC₆F₅)[OC(CF₃)₃](PMe₃)₂.

Electronic effects in mixed N-heterocyclic carbene/phosphite indenylidene ruthenium metathesis catalysts

Five new complexes [RuCl₂(SIMes)(Ind)(O-pXC₅H₄)] bearing different para-substituted triphenylphosphites (X = H, OCH₃, CF₃, Cl, SF₅ and CN) were synthesised and used to study the effect of the electronic properties of the phosphite on olefin metathesis activity. Investigations of the physical properties of the new ligands and complexes were performed using physicochemical and DFT calculations. The catalytic activity of the complexes was benchmarked in challenging ring closing metathesis transformations featuring the formation of tetra-substituted double bonds. Complex [RuCl₂(SIMes)(Ind)P(O-pCF₃C₅H₄)₃] (3c) exhibited a particularly high catalytic activity, superior to state-of-the-art catalysts, and was further tested on a wide range of substrates.