Mixed Metal Clusters

Author : Po-Kwan Jasmine Lau
Publisher : Open Dissertation Press
ISBN 13 : 9781361426869
Total Pages : pages
Book Rating : 4.4/5 (268 download)

DOWNLOAD NOW!

Download or read book The Chemistry of Mixed-Metal Clusters of Osmium and Rhodium written by Po-Kwan Jasmine Lau and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "The Chemistry of Mixed-metal Clusters of Osmium and Rhodium" by Po-kwan, Jasmine, Lau, 劉寶君, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. Abstract: Abstract of thesis entitled THE CHEMISTRY OF MIXED-METAL CLUSTERS OF OSMIUM AND RHODIUM Submitted by LAU PO KWAN JASMINE for the degree of Doctor of Philosophy at The University of Hong Kong in December 2005 The general background of metal clusters, the chemistry of osmium-rhodium mixed-metal clusters, and their potential catalytic applications are reviewed. The work in the synthesis, characterizations, and reactivity studies of different series of osmium-rhodium mixed-metal clusters help us to understand the properties and reactivities of new clusters as compared to the bulk metal surface. 1 1 1 A novel face-capping mode of toluene was observed in [Os Rh (μ -η η η - 3 4 3 C H CH )(CO) ] 1. Cluster 1, together with [Os Rh(-H)(η -C H CH )(CO) ] 2 6 5 3 13 4 6 5 3 12 and a known compound [Os Rh (η -C H CH )(-CO)(CO) ], were obtained from 5 2 6 5 3 16 the reaction of [Os Rh(μ-H) (CO) ] with toluene in the presence of an excess 3 3 12amount of 4-vinylphenol. The reaction of [Os Rh(-H) (CO) ] with an excess 3 3 12 amount of 4-vinylphenol (as a hydride acceptor) in refluxing m-xylene, chlorobenzene, or benzene yielded three new clusters [Os Rh {η -C H (CH ) } 5 2 6 4 3 2 6 6 (-CO)(CO) ] 3, [Os Rh (η -C H Cl)(-CO)(CO) ] 4, and [Os Rh (η -C H ) 16 5 2 6 5 16 5 2 6 6 (-CO)(CO) ] 5, respectively. 16 The hydrogenation of [Os Rh (η -C H CH )(-CO)(CO)] with 5 2 6 5 3 16 [Os (-H) (CO) ] resulted in moderate yields of two hydrogen-rich compounds: 3 2 10 [Os Rh (-H) (CO) ] 6 and [Os Rh Cl(-H) (CO) ] 7. The reaction of 7 3 11 23 5 3 8 18 [Os Rh (η -C H CH )(-CO)(CO) ] with hydrogen yielded a new cluster 5 2 6 5 3 16 compound, [Os Rh(-H) (CO) ] 8. A deuterium exchange experiment was 5 5 18 performed on 6, and 7. Both the compounds proved to be able to exchange the H atom with D in the presence of D SO, and the absence of the hydride signal in the 2 4 H NMR spectrum is consistent with this. Therefore, clusters 6 and 7 may serve as appropriate new hydrogen storage models. A detailed discussion of the chemistry of anionic osmium-rhodium mixed-metal clusters with Au cationic fragments using [Au(PPh )Cl] and [(AuCl) L-L], where L 3 2 = dppe (bis(diphenylphosphino)ethane) or dppp (bis(diphenylphosphino)propane), is presented. Two mono-anionic osmium-rhodium mixed-metal clusters [PPN][Os Rh(μ-CO)(CO) ] 9 and [PPN][Os Rh (μ-CO) (CO) ] 10 were prepared 6 19 9 3 2 26 by the thermolysis of [Os Rh(μ-H) (CO) ]. Electrochemistry studies on 10 showed 3 3 12 four successive redox couples, and revealed a novel electron reservoir property. Treatment of 9 with two equivalent of [Au(PPh)Cl] gave compounds [Os Rh Au(CO) (PPh )] 11, and [Os Au (CO) (PPh ) ][Os Rh(μ-CO)(CO) ] 12. 4 3 18 3 5 3 15 3 3 6 19 Both compounds successfully demonstrated the introduction of the Au(PR ) units 3into transition-metal clusters. Two linked clusters [{Os RhAu(μ-CO)(CO) } (dppp)] 6 19 2 13 and [{Os RhAu(μ-CO)(CO) } (dppe)] 14 were prepared by the reaction of 9 6 19 2 with two equivalent [(AuCl) dppp] and [(AuCl) dppe], respectively. 2 2 The synthesis and characterization of linked cluster [{Os (CO) (μ -H)} 3 10 2 2 {μ,μ -NC H C H N}] 15 from the reaction of [Os Rh(μ-H) (CO) ] with aniline in 2 2 6 4 6 4 3 3 12 the presence of an excess amount of 4-vinyl phenol