Surface organometallic chemistry:  hydrogenation of ethylene with Os3(CO)10(.mu.-H)(.mu.-OSi.rscharw.) and Os3(CO)10(.mu.-H)(.mu.-OPh).  Evidence for cluster catalysis

Choplin, A.; Besson, Bernard; D'Ornelas, Lindora; Sánchez‐Delgado, Roberto A.; Basset, J. M.

doi:10.1021/ja00217a015

Cited by 55 publications

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“…If the surface organometallic fragment has a unique structure (unfortunately not always the case), it is straightforward to deduce the electronic configuration of the metal. Based on the (6,8,10,12,14,16,18,20) electron rule, one can predict the electrophilic or nucJeophilic character of the metal. The following examples demonstrat.e how characterisation of surface organometallic species has enabled us to rationalize their structure and electronic configuration using concepts from organometallic chemistry.…”

Section: Structure and Electronic Configuration Of Surface Organometamentioning

confidence: 99%

“…The supported cluster (fl-0-Si",)(!-"-H)OS3(CO)1O, 1 [10], is an 18-electron cJuster in which a surface oxygen atom of silica behaves as a 3-electron ligand (in the MLH Green formalism) to the cJ uster. The magnesia-supported ruthenium cl uster [HRu3(CO) I JJ-, 2, represents a case in which the surface does not participate in formation of a covalent bond, but merely acts as a counter-cation which neutralizes the charge of the supported cluster 16J.…”

Section: Structure and Electronic Configuration Of Surface Organometamentioning

confidence: 99%

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Organometallic Chemistry as a Basis for Understanding Heterogeneous Catalysis

Basset¹,

Scott²,

Choplin³

et al. 1993

Elementary Reaction Steps in Heterogeneous Catalysis

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At the present time, our knowledge of the mechanism of action of most heterogeneous catalysts is limited. At the most primitive level, only the overall product distribution is known, while the nature of the catalyst-reactant interactions remains obscure. In a few cases, more detailed mechanistic proposals have been advanced, but they remain modest in scope compared to the detailed mechanisms that have been developed in molecular organic chemistry, and more recently, in organometallic chemistry. Indeed, even the apparently well-established catalytic mechanisms (for example, hydrogenation of olefins) are sometimes contested, indicating the fragility of the evidence on which these proposals are based. It must be recognized, however, that by comparison to strictly molecular systems, heterogeneous catalysts are intrinsically much more complicated. In addition, the application of physical methods to structural and mechanistic problems of heterogeneous systems, as well as interpretation of the results, can be difficult.A common problem encountered in heterogeneous catalysis is the complexity of the surfaces of solid catalysts. The so-called "active sites", a concept proposed by Sir H. S. Taylor [II. may be very small in number relative to the overall surface and, consequently, their structure is almost unknown at an atomic level. It is probably this complexity which has inspired the development of surface science applied to catalysis. New concepts have emerged slowly from this approach: surface reconstruction in the presence of adsorbed molecules, surface mobility and structural reorganization of molecular-like species. It has been demonstrated that the binding of chemisorbed molecules resembles organometallic ligation (e.g., YJ l, 11 2 and YJ3-adsorbed CO, Jt-bound ethylene and YJ l, YJ2 and YJ5-ethylidene species) 12]. Naturally, the concepts derived from surface science have been, for the most part, applied to the chemisorption process and not to the reactiv ity pattern, although the latter is, in fact, the key to catalytic mechanisms.At a fundamental level, we are interested in the elementary steps of heterogeneous catalytic mechanisms, that is, the succession of chemical events in which bonds of a substrate molecule are broken or created in the proximity of the surface. The number of examples in which this sllccession of events has been demonstrated on a well-defined surface is still limited. However, a growing awareness of this deficiency has spurred the recent development of surface organometallic chemistry 13]. In this relatively new field, the organometallic character of the "active site" is exploited in order to model reaction mechanisms.During a catalytic cycle, substrates which interact with the surface form one or several chemical bonds with one or several surface atoms. Hence the "active site" is a 39 R. W. Joyner and R. A. van Santen (eds.), Elementary Reaction Steps in Heterogeneous Catalysis,[39][40][41][42][43][44][45][46][47][48][49]

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Section: Structure and Electronic Configuration Of Surface Organometamentioning

confidence: 99%

Section: Structure and Electronic Configuration Of Surface Organometamentioning

confidence: 99%

Organometallic Chemistry as a Basis for Understanding Heterogeneous Catalysis

Basset¹,

Scott²,

Choplin³

et al. 1993

Elementary Reaction Steps in Heterogeneous Catalysis

View full text Add to dashboard Cite

show abstract

“…Starting from these evidences, the chemistry of these molecular surface organometallic species was clearly parallel to their well -known organometallic chemistry in solution [36] . 10 ] and its molecular analog ( μ -O -C 6 H 5 )Os 3 ( μ -H)(CO) 10 are catalysts in the heterogeneous and homogeneous phase, respectively, for ethylene hydrogenation [37] . The cluster frame was kept intact thanks to the ligand character of the surface oxygen, which could become μ -2 or μ -1 in the various elementary steps of the catalytic cycle (Scheme 1.4 ).…”

Section: Foundation Of Surface Organometallic Chemistrymentioning

confidence: 99%

On the Origins and Development of “Surface Organometallic Chemistry”

Basset

Ugo

2009

Modern Surface Organometallic Chemistry

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“…Early investigations by Shapley [12], Basset [13], and Gladfelter [14] Basset's proposal for the silica-supported cluster [Os 3 (CO) 10 (l-H)(l-OSi)] was made on the basis of surface IR spectroscopy studies, kinetic and gas uptake measurements, and reactions of the soluble analogue [Os 3 (CO) 10 (l-H)(l-OSi-Ph)]; the supported catalyst hydrogenated ethylene at 90 8C and atmospheric pressure in a flow reactor at a TOF of 144 h -1 for extended periods of time, achieving up to 24 000 turnovers overall. Gladfelter also used kinetic measurements and IR spectroscopy to deduce the mechanism of alkene hydrogenation by anionic clusters containing isocyanate ligands [Ru 3 (l-NCO) (CO) 10 ] -; this catalyst reduced 3,3-dimethylbutene at rates of about 300 to 360 turnovers h -1 under ambient conditions.…”

Section: Hydrogenation Of CC Bondsmentioning

confidence: 99%

“…Early studies by Ugo and Braunstein led to low-activity bimetallic catalysts [52]. [RuFe 2 (CO) 12 ], [Ru 2 Fe(CO) 12 ] and [Ru 3 FeH 2 (CO) 13 ] were studied by Giordano and Sappa [32]; these promote the hydrogenation of diphenylacetylene at lower rates than the homonuclear Ru clusters, and the nature of the active species was not established. Süss-Fink and coworkers reported the use of [IrRu 3 (CO) 13 (l-H)] in the hydrogenation of diphenylacetylene, curiously to E-stilbene (TOF 3900 h -1 ), and proposed a cycle involving cluster intermediates [53].…”

Section: Hydrogenation Of CC Bondsmentioning

confidence: 99%

Homogeneous Hydrogenation by Defined Metal Clusters

Sánchez‐Delgado¹

2006

The Handbook of Homogeneous Hydrogenation

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The catalytic potential of well-defined transition-metal clusters in homogeneous reactions has attracted a great deal of attention over the years, as they represent a natural bridge between mononuclear complexes, metal nanoparticles, and metal-oxide, -sulfide and related surfaces used in heterogeneous catalysis. The molecular nature of metal clusters, together with their solubility properties, provides the advantages of classical mononuclear homogeneous catalysts (high activity, high selectivity, moderate operating conditions, possibility of catalyst design and modification), while the polynuclear framework can offer the possibility of multi-metallic cooperative effects often identified as a key element in the desirable properties of solid heterogeneous catalysts. Therefore, metal clusters can be expected, in principle, to combine the positive aspects of homogeneous and heterogeneous catalytic reactions and, perhaps more importantly, they may react through unique pathways associated with the cluster structures and thereby catalyze reactions not accessible by mononuclear or heterogeneous catalysts. Nevertheless, despite the impressive amount of work that has been devoted to develop these concepts over several decades, the great expectations first advanced during the mid-1970s have not yet been fully accomplished [1][2][3][4][5][6].From a different perspective, well-defined metal clusters have served as useful models for discerning the complex mechanisms of heterogeneous catalytic systems. The structural trends for metal clusters are now well understood, and their reactions in solution can be studied in detail by relatively simple chemical and spectroscopic methods, thereby producing important information at the molecular level -something that is very difficult to achieve on solid catalysts. The knowledge thus gained from studying metal cluster chemistry can be extrapolated, with adequate caution, to heterogeneous reactions [1][2][3][4][5][6].Another trend that has received considerable recent attention is the decomposition of metal clusters under controlled conditions on solid supports or on liquid suspensions, which generates small metallic particles of specific size, struc- 199The Handbook of Homogeneous Hydrogenation. Edited by J. G. de Vries and C. J. Elsevier

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Surface organometallic chemistry: hydrogenation of ethylene with Os3(CO)10(.mu.-H)(.mu.-OSi.rscharw.) and Os3(CO)10(.mu.-H)(.mu.-OPh). Evidence for cluster catalysis

Cited by 55 publications

References 0 publications

Organometallic Chemistry as a Basis for Understanding Heterogeneous Catalysis

Organometallic Chemistry as a Basis for Understanding Heterogeneous Catalysis

On the Origins and Development of “Surface Organometallic Chemistry”

Homogeneous Hydrogenation by Defined Metal Clusters

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