Surface organometallic approach

J2.10 A surface organometallic approach to the process of formation of bimetallic particles from bimetallic supported molecular clusters... 

In summary, we have described our approach towards the synthesis of novel nano-objects consisting of a metal core and a surface that may be functionalized by addition of organic ligands. TEM pictures of the metal core of these nanoparticles appear similar to those of particles commonly used in heterogeneous catalysis or to colloids prepared by well-known reduction methods. However, the organometallic approach displays several specificities which can be summarized as follows ... 

Basset, J. M., Gates, B. C., Candy, J. P., Choplin, A., Leconte, M., Quignard, E, and Santini, C. C., Surface Organometallic Chemistry Molecular Approaches to Surface Catalysis, NATO ASI Series, Kluwer, Dordrecht, 1988. 

Y. A. Ryndin, and Y. I. Yermakov, Reactions of organometallic compounds with surfaces of supported and unsupported metals. In Surface Organometallic Chemistry Molecular Approaches to Catalysis edited by J. -M. Basset, B. C. Gates, J.-P. Candy, A. ChopUn, M. Lecomte, F. Quignard, and C. Santini (Kluwer, Dordrecht 1998) pp. 127-141. 

In this unusual and new synthetic approach the surface of the inorganic oxide does not behave as a new medium for dispersion of reagents but as a particular kind of ligand that by binding, in various ways, surface organometallic molecular fragments or species controls both the kinetic and the selectivity of the reactions taking place on the surface. 

Surface Organometallic Chemistry on Metals (SOMC/M) Approach... 

The studies discussed above deal with highly dispersed and therefore well-defined rhodium particles with which fundamental questions on particle shape, chemisorption, and metal support interactions can be addressed. Often, such catalysts are prepared from different starting materials, such as organometallic clusters [28] and carbonyls [29] than are used in industry. Noteworthy are also the studies on evaporated rhodium clusters on planar supports, as have been studied extensively in surface science approaches [5, 30-32]. 

Basset J-M, Gates BC, Candy J-P, Choplin A, Leconte M, Quignard F, Santini C (eds) (1988) Surface organometallic chemistry molecular approaches to surface catalysis. NATO ASl series, vol 231. Kluwer, Dordrecht... 

Methods of Controlled Surface Reactions (CSRs) and Surface Organometallic Chemistry (SOMC) were developed with the aim to obtain surface species with Sn-Pt interaction. In CSRs two approaches have been used (i) electrochemical, and (ii) organometallic. Characteristic feature of the organometallic approach is that both CSR and SOMC results in almost exclusively supported alloy type bimetallic nanoclusters. Studies on the reactivity of tin organic compounds towards hydrogen adsorbed on different transition and noble metals have revealed new aspects for the preparation of supported bimetallic catalysts. 

Preparation of Alloy Type Sn-Pt/Si02 Catalysts. Supported bimetallic Sn-Pt catalysts can be prepared using different methods and approaches. However, exclusive formation of alloy type nanoclusters can be achieved by using methods of surface organometallic chemistry, namely by applying Controlled Surface Reactions (CSRs) between hydrogen adsorbed on platinum and tin tetraalkyls. 

R.D. Adams and W.A. Herrmann (Eds.), Chemistry of Heteronuclear Clusters and Multimetallic Catalysts, Kdnigstein, Germany, September 1987 [Polyhedron Symposium-in-Print No. 8]. Polyhedron, 1988, 7 (22/23), pp. 2251-2463 J,-M. Basset, B.C. Gates, J.P. Candy, A. Choplin, M. Leconte, F. Quignard and C. Santini (Eds.), Surface Organometallic Chemistry Molecular Approaches to Surface Catalysis [NATO ASI Ser., vol. C231], Kluwer Dordrecht, 1988 P. Braunstein (ed.). Recent Advances in Di- and Polynuclear Chemistry, New J. Chem., 1988, 12 (6/7), pp. 305-720... 

The preparation of unsupported metal nanoparticles was therefore achieved following an organometallic approach since this does not employ drastic reaction conditions and avoids surface contamination. In addition, the size, the shape and the surface state of the particles can be controlled using various stabilizing agents. Besides catalysis, such work can find applications in different areas such as chemical sensors [141, 142] or magnetic properties [143]. 

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