A Heterogeneous Ruthenium dmso Complex Supported onto Silica Particles as a Recyclable Catalyst for the Efficient Hydration of Nitriles in Aqueous Medium

Abstract

In the present work, we describe an efficient method for the covalent anchoring of a Ru-dmso complex onto two types of supports: mesoporous silica particles (SP) and silica coated magnetic particles (MSNP). First, we have prepared and characterized the molecular complexes containing the bidentate pyridylpyrazole ligands pypz-Me and pypz-CH2­COOEt, with the formula [RuIICl2­(pypz-R)­(dmso)2] (R = Me, 1; CH2COOEt, 2). Complex 2 was anchored onto the silica supports, yielding the heterogeneous systems SP@2 and MSNP@2 which were fully characterized by IR, UV–vis, SEM, TEM, TGA, and XPS techniques. Hydration of representative nitriles has been tested with the molecular complexes and their SP@2 and MSNP@2 heterogeneous counterparts, in aqueous medium under neutral conditions. The heterogeneous catalysts display high yields and excellent selectivity values. Both systems can be reused throughout several cycles for benzonitrile and acrylonitrile substrates, without any significant loss in reactivity. The MSNP@2 material can be easily recovered by a magnet, facilitating its reusability.

Enhancing Photoredox Catalysis in Aqueous Environments: Ruthenium Aqua Complex Derivatization of Graphene Oxide and Graphite Rods for Efficient Visible-Light-Driven Hybrid Catalysts

“…These values of binding energies observed in the XPS spectra for ruthenium reveal the presence of Ru(II) species in the hybrid material. 47,48 The UV−visible spectrum of GO@trans-fac-3 registered on a suspension of the heterogeneous support in dichloromethane exhibits a similar pattern to that of the homogeneous compound, observing the band corresponding to dπ(Ru)π*(L) MLCT transitions around 460 nm, in agreement with that observed in the aqua complex trans-fac-3 (Figure S15).…”

“…Another peak observed at ∼463 eV could be assigned to Ru(3p 3/2 ) (Figure S14). These values of binding energies observed in the XPS spectra for ruthenium reveal the presence of Ru(II) species in the hybrid material. , …”

“…These values of binding energies observed in the XPS spectra for ruthenium reveal the presence of Ru(II) species in the hybrid material. 47 , 48 …”

Noncovalently Linked Metallacarboranes on Functionalized Magnetic Nanoparticles as Highly Efficient, Robust, and Reusable Photocatalysts in Aqueous Medium

“…To overcome this, the MNPs can be coated with a layer of material leading to core–shell magnetic particles for their stabilization and producing a favorable surface on which to link the active sites. Such materials combine the unique magnetic properties of the core with the possibility to further functionalize the surface; , , in addition, the application of an external magnetic field enables the removal of the particles in a simple way. − Among the coatings of these nanoparticles, silica has been widely used due to its inert properties and because it helps in improving the stability and the physicochemical properties of the MNPs, preventing their aggregation in solution. − The most important aspect of MNPs coated with silica is that the silanol-terminated surface groups may be modified with various coupling agents to covalently bind to specific ligands. , This helps to tune the surface of these MNPs coated with silica with different functional groups to obtain differently functionalized MNPs, which can be further used for different purposes. Thus, efficient recyclable photocatalysts based on noble metal nanoparticles have been used, improving the performance of the photocatalytic processes. , It is to be noted that throughout this introduction we have been talking about covalent bonds either from the ligand to the silica layer or from the ligand to the metal.…”