Supported molecular clusters

Analogy between Supported Molecular Clusters and Small Supported Catalytic Particles... 

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

AN INTRODUCTION TO THE FIELD OF CATALYSIS BY MOLECULAR CLUSTERS AND BY SUPPORTED MOLECULAR CLUSTERS AND COMPLEXES... 

The last section contains two unusual examples of catalytic processes, namely photochemically induced catalysis and supported molecular cluster catalysis. The latter is a new and promising area of research, since it combines the advantages of both heterogeneous and homogeneous catalysis. 

Figure A. Transformations observed between supported molecular cluster and active catalyst for 053(00)J2/Si02 in the presence of carbon monoxide and hydrogen.

Hi ly dispersed supported bimetallic catalysts with bimetallic contributions have been prepared from molecular cluster precursors containing preformed bimetallic bond [1-2]. For examples, extremely high dispersion Pt-Ru/y-AUOa could be prepared successfully by adsorption of Pt2Ru4(CO)ison alumina [2]. By similar method, Pt-Ru cluster with carbonyl and hydride ligands, Pt3Ru6(CO)2i(p3-H)(p-H)3 (A) was used in this work to adsorb on MgO support. The ligands were expectedly removable from the metal framework at mild conditions without breaking the cluster metal core. 

The final probe of molecular clusters is that of selected chemical reactions. The use of probe reactions to study supported cluster catalysts is well established, and we are attempting the development of similar probes of unsupported clusters. The first steps in this direction are the design of a pulsed chemical reactor to go with the pulsed cluster source and the development of criteria for reactions. It is important to recall that at present... 

Oxide- and Zeolite-supported "Molecular" Metal Clusters Synthesis, Structure, Bonding, and Catalytic Properties... 

Abstract This review is a summary of supported metal clusters with nearly molecular properties. These clusters are formed hy adsorption or sirnface-mediated synthesis of metal carbonyl clusters, some of which may he decarhonylated with the metal frame essentially intact. The decarhonylated clusters are bonded to oxide or zeolite supports by metal-oxygen bonds, typically with distances of 2.1-2.2 A they are typically not free of ligands other than the support, and on oxide surfaces they are preferentially bonded at defect sites. The catalytic activities of supported metal clusters incorporating only a few atoms are distinct from those of larger particles that may approximate bulk metals. 

Oxide- and Zeolite-Supported Molecular Metal Clusters... 

The literature of metal-support interactions includes httle about the possible chemical bonding of metal clusters or particles to supports. Supported molecular metal clusters with carbonyl ligands removed have afforded opportunities to understand the metal-support interface in some detail, and the results provide insights into the bonding of clusters to supports that appear to be generalizable beyond the small clusters to the larger particles of conventional supported metal catalysts [6]. 

Gates BC (2005) Oxide- and Zeolite-supported Molecular Metal Clusters Synthesis, Structure, Bonding, and Catalytic Properties. 16 211-231 Gibson SE (nee Thomas), Keen SP (1998) Cross-Metathesis. 1 155-181 Gisdakis P, see Rosch N (1999) 4 109-163 Gdrling A, see Rosch N (1999) 4 109-163... 

Nashner MS, Frenkel Al, Adler DL, Shapley JR, Nuzzo RG. 1997. Structural characterization of carbon supported platinum-ruthenium nanoparticles from the molecular cluster precursor PtRu5(CO)i6. J Am Chem Soc 119 7760. 

Fierro-Gonzalez, J.C., Kuba, S., Hao, Y. et al. (2006) Oxide- and zeolite-supported molecular metal complexes and clusters physical characterization and determination of structure, bonding, and metal oxidation state, J. Phys. Chem. B, 110, 13326. 

Molecular Clusters as Precursors to Supported Metal Catalysts... 

J. Guzman and B. C. Gates, Supported molecular catalysts metal complexes and clusters on oxides and zeolites, Dalton Trans. 17, 3303—3318 (2003). 

B. D. Chandler, A. B. Schabel, C. F. Blanford, and L. H. Pignolet, The preparation and characterization of supported bimetallic Pt-Au particle catalysts from molecular cluster and chloride salt precursors, J. Catal. 367-383 (1999). 

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