Hydrogenolysis of C-O Chemical Bonds of Broad Scope Mediated by a New Spherical Sol-Gel Catalyst.

The new spherical sol-gel hybrid material Silia Pd selectively mediates the hydrogenolysis of aromatic alcohols, aldehydes, and ketones by using an ultralow catalytic amount (0.1 mol % Pd) under mild reaction conditions. The broad reaction scope as well as the catalyst's superior activity and pronounced stability open the route to green and convenient reductive deoxygenation processes of primary synthetic relevance in chemical research as well as in the fine chemical and petrochemical industries.

Solvent-Free Chemoselective Hydrogenation of Squalene to Squalane.

Squalene is selectively and entirely converted into squalane over the spherical sol-gel-entrapped Pd catalyst Silia Pd(0) under solvent-free and mild reaction conditions of 3 bar H and 70 °C. The catalyst was reused successfully in eight consecutive cycles, with palladium leaching values <2 ppm, opening the route to sustainable and less-expensive hydrogenation of phytosqualene with important sustainability consequences.

Sol-gel encapsulation of Au nanoparticles in hybrid silica improves gold oxidation catalysis.

Background: The introduction of an heterogeneously catalyzed gold-based alcohol oxidation process of broad applicability using a clean primary oxidant would be highly desirable. Gold is non toxic and carbonyl and carboxyl compounds are widely used to produce medicines, plastics, colorants, paints, detergents, fragrances, flavors, and other valued functional products.

Results: The sol-gel entrapment of gold nanoparticles in hybrid silica improves gold-based oxidation catalysis applied to the selective oxidation of alcohols with aqueous hydrogen peroxide as eco-friendly primary oxidant.

Clean and fast cross-coupling of aryl halides in one-pot.

Unsymmetrically coupled biaryls are synthesized in high yield starting from different aryl bromides and bis(pinacolato)diboron by carrying out the Miyaura borylation reaction followed by the Suzuki-Miyaura reaction in the same reaction pot over 1-2 mol % SiliaCat DPP-Pd. The SiliaCat DPP-Pd catalyst is air-stable and the method does not require the use of inert conditions. The use of non-toxic isopropanol or 2-butanol as reaction solvent further adds to the environmental benefits of this new green synthetic methodology.

Towards waste free organic synthesis using nanostructured hybrid silicas.

As catalysis and organic synthesis come together again, the need for stable, selective and truly heterogeneous solid catalysts for clean and efficient synthetic organic chemistry has increased. Hybrid silica glasses obtained by the sol-gel nanochemistry approach can be successfully used for the waste-free synthesis of valued chemicals in various applications. This success derives from the deliberate chemical design of hybrid nanostructures capable of immobilizing and stabilizing organocatalytic species and unstable metal nanoparticles.

The sol-gel entrapment of noble metals in hybrid silicas: a molecular insight.

Background: Why are metal nanoparticles sol-gel entrapped in ORMOSIL so active and stable? In other words, why ORMOSIL-entrapped metal nanoparticles are more active and selective than many heterogenized counterparts, including silica-entrapped noble metals?

Results: Unveiling specific interactions between MNPs and the molecular structure of ORMOSIL, this work investigates subtle structural aspects through DRIFT spectroscopy.

Conclusions: The results point to interactions between entrapped Pd and Pt nanocrystallites with the organosilica sol-gel cages similar to those taking place in enzymes.

Ni(II) complexes featuring non-metallated pincer-type ligands.

Attempts to prepare pincer-type Ni complexes from the ligands (i-Pr(2)POCH(2))(2)CH(2) and (pz*CH(2))(2)CH(2) (pz* = 3,5-dimethylpyrazol-1-yl) gave instead the complexes cis-{kappa(P),kappa(P')-(i-Pr(2)POCH(2))(2)CH(2)}NiCl(2) and {kappa(N),kappa(N')-(pz*CH(2))(2)CH(2)}NiBr(2). X-Ray diffraction studies confirmed that these potentially pincer-type ligands have not undergone metallation, serving instead as chelating ligands in essentially square-planar or tetrahedral complexes. Heating of these compounds failed to induce metallation of the coordinated ligands.

New pincer-type diphosphinito (POCOP) complexes of NiII and NiIII.

This communication reports the synthesis and characterization of the new, pincer-type, square-planar, 16-electron compounds {2,6-(OPPr(i)(2))(2)C(6)H(3)}Ni(II)Br, 1, and {(Pr(i)(2)POCH(2))(2)CH}Ni(II)Br, 2, and the square-pyramidal, 17-electron complex {(Pr(i)(2)POCH(2))(2)CH}Ni(III)Br(2), 3.