The development of more effective alkane dehydrogenation catalysts is a key technological challenge for the production olefins from shale gas, an abundant source light hydrocarbons. Surface organometallic chemistry provides original approach to generate nanometric Ga–Pt bimetallic particles supported on partially dehydroxylated silica containing gallium single-sites, which displays high activity, selectivity, and stability in propane dehydrogenation. This catalyst was prepared via sequential...

Molybdenum-based molecular alkylidyne complexes of the type [MesC≡Mo{OC(CH3)3–x(CF3)x}3] (MoF0, x = 0; MoF3, 1; MoF6, 2; MoF9, 3; Mes 2,4,6-trimethylphenyl) and their silica-supported analogues are prepared characterized at level, in particular by solid-state NMR, alkyne metathesis catalytic activity is evaluated. The 13C NMR chemical shift carbon increases with increasing number fluorine atoms on alkoxide ligands for both supported catalysts but more shielded values complexes. these order...

Alkene metathesis is a widely and increasingly used reaction in academia industry because of its efficiency terms atom economy wide applicability. This notably responsible for the production several million tons propene annually. Such industrial processes rely on inexpensive silica-supported tungsten oxide catalysts, which operate at high temperatures (>350 °C), contrast with mild room temperature conditions typically corresponding molecular alkene homogeneous catalysts. large difference...

CuGa<italic>x</italic> alloy nanoparticles supported on SiO₂ can be obtained by surface organometallic chemistry. This catalyst is active and selective for the hydrogenation of CO₂ to CH₃OH, related formation an optimal interface between Cu Ga^IIIO<italic>x</italic>.

The catalytic properties of a series ruthenium complexes for H/D exchange between D2O and alcohols were studied. activity the regioselectivity reactions found to be dependent on auxiliary ligands. While η6-cymene such as [(η6-cymene)RuCl(NH2CH2CH2NTs)]Cl, (η6-cymene)RuCl2/NH2CH2CH2OH, (η6-cymene)Ru{(S,S)-NHCHPhCHPhNTs} catalyzed regioselective deuteration with at β-carbon positions only, octahedral RuCl2(2-NH2CH2Py)(PPh3)2 (2-NH2CH2Py = 2-aminomethylpyridine) RuCl2(NH2CH2CH2NH2)(PPh3)2 both...

A well-defined silica-supported molybdenum dioxo species, (SiO)₂Mo(O)₂, prepared <italic>via</italic> Surface Organometallic Chemistry, is highly active in metathesis upon reaction with organosilicon reducing agent.

Abstract Viele industrielle Katalysatoren enthalten isolierte Metallzentren an der Oberfläche von Oxidträgern. Derartige werden seit über 40 Jahren bei verschiedensten Verfahren verwendet – die Struktur ihrer katalytischen Zentren bleibt aber bis heute nur ungenügend verstanden. Dieser Aufsatz zeigt, wie mit metallorganischer Oberflächenchemie (SOMC) Oberflächenzentren gut definierten Strukturen erzeugt können, und beschreibt Beschaffenheit aktiver in industriellen Katalysatoren,...

The structural characterization of supported molecular catalysts is challenging due to the low density active sites and presence several organic/organometallic surface groups resulting from often complex chemistry associated with support functionalization. Here, we provide a complete atomic-scale description all in an N-heterocyclic carbene based on iridium silica, at stages its synthesis. By combining suitable isotope labeling strategy implementation multinuclear dipolar recoupling...

In alkene metathesis, while group 6 (Mo or W) high-oxidation state alkylidenes are accepted to be key reaction intermediates for both homogeneous and heterogeneous catalysts, it has been proposed that low valent species in their +4 oxidation can serve as precatalysts. However, the activation mechanism these latter species—generating alkylidenes—is still an open question. Here, we report syntheses of tungsten(IV)–oxo bisalkoxide molecular complexes stabilized by pyridine ligands, WO(OR)2py3...

Despite the importance of heterogeneous tungsten–oxo-based olefin metathesis catalyst (WO3/SiO2) in industry, understanding its initiation mechanism is still very limited. It has been proposed that reduced W(IV)–oxo surface species act as precatalysts. In order to understand reactivity and species, we synthesized a well-defined silica-supported (≡SiO)WO(OtBuF6)(py)3 (F6@SiO2–700; OtBuF6 = OC(CH3)(CF3)2; py pyridine), via organometallic chemistry (SOMC). F6@SiO2–700 was shown be highly active...

Abstract Designing highly active supported ethylene polymerization catalysts that do not require a co‐catalyst to generate electrophilic metal alkyl species is still challenge despite its industrial relevance. Described herein the synthesis and characterization of well‐defined silica‐supported cyclopentadienyl Ln II sites (Ln=Yb Sm) general formula [(≡SiO)LnCp*]. These surface are activite towards in absence added co‐catalyst. Initiation proposed occur by single electron transfer.

Phosphines can efficiently catalyze alkenylation of <italic>o</italic>-carborane with electron-deficient alkynes, which represents the first example organocatalysis in functionalization.

Abstract Manganese, the third most abundant transition‐metal element after iron and titanium, has recently been demonstrated to be an effective homogeneous catalyst in numerous reactions. Herein, preparation of silica‐supported Mn II sites is reported using Surface Organometallic Chemistry (SOMC), combined with tailored thermolytic molecular precursors approach based on 2 [OSi(O t Bu) 3 ] 4 Mn{N(SiMe ) } ⋅THF. These supported sites, free organic ligands, efficiently catalyze reactions:...

Abstract Here we present our observations on a peculiar kinetic behavior observed at low catalyst loadings for the metathesis of internal olefins highly active silica‐supported tungsten oxo alkylidene prepared through surface organometallic chemistry (SOMC). The profile is comprised two consecutive regimes, which support presence different sites such catalysts. We propose that more site operational in beginning reaction but deactivates very fast, and second one initiates over time due to...

Treatment of [Re(dppm)3]I (dppm = PPh2CH2PPh2) with HC≡CPh produced the rhenium vinylidene complex ReI(═C═CHPh)(dppm)2. In presence HI, reacted HC≡CR (R Ph, p-tolyl, C6H4-o-CHO, (CH2)5CH3) to give carbyne complexes [ReI(≡CCH2R)(dppm)2]I and HC≡CSiMe3 [ReI(≡CMe)(dppm)2]I. One-pot reactions [Re(dppm)3]I, HC≡CC(OH)RR′ (RR′ Ph2, Me2, PhMe), HI vinylcarbyne [ReI(≡CCH═CRR′)(dppm)2]I.

Abstract Designing highly active supported ethylene polymerization catalysts that do not require a co‐catalyst to generate electrophilic metal alkyl species is still challenge despite its industrial relevance. Described herein the synthesis and characterization of well‐defined silica‐supported cyclopentadienyl Ln II sites (Ln=Yb Sm) general formula [(≡SiO)LnCp*]. These surface are activite towards in absence added co‐catalyst. Initiation proposed occur by single electron transfer.

Abstract 5‐Coordinated methoxybenzylidene complexes M(=NAr)(=CH−C 6 H 4 − o ‐OMe)(O t Bu F3 ) 2 (Ar=2,6‐ i Pr C 3 ; =CMe (CF )) of Mo ( 1m and W were synthesized by cross‐metathesis from the corresponding neophylidene/neopentylidene precursors ‐methoxystyrene. grafted onto surface silica partially dehydroxylated at 700 °C to give well‐defined silica‐supported alkylidenes (≡SiO)M(=NAr)(=CH−C (M=Mo 1 ), )). Supported tested in metathesis cis ‐4‐nonene, 1‐nonene, ethyl oleate, compared their...

Olefin metathesis is a versatile strategy for large-scale olefin interconversion, yet mechanistic details over industrial heterogeneous catalysts have remained ambiguous decades. Here, from rigorous kinetic measurements, spectroscopic studies, and computational modeling of propylene model WOx/SiO2 catalysts, we identify hitherto unknown site renewal decay cycle, mediated by proton transfers involving proximal Brønsted acidic OH groups, which operates concurrently with the classical Chauvin...

Abstract γ ‐Alumina supported 3d transition‐metal nanoparticles are commonly used catalysts for several industrial reactions, such as Fischer‐Tropsch , reforming, methanation, and hydrogenation reactions. However, the activity of catalyst is often limited by low metal dispersion a high content irreducible metal, inherent to conventional preparation methods in aqueous phase. In this context, we have recently shown that [{Ni( μ 2 ‐OCHO)(OCHO)(tmeda)} ( ‐OH )] (tmeda=tetramethylethylenediamine)...