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Cyclodextrin-modified phosphine ligands and their metal complexes and reactions of terminal acetylenes with M(PCP) complexes

Authors Cheung, Yuk King
Issue Date 1997
Summary The combination of molecular recognition and transition metal catalysis could lead to an interesting form of supramolecular catalysis. Thus, it would be interesting to synthesize phosphine ftmctionalised cyclodextrins and to investigate their uses in catalysis. We have developed several routes to phosphine functionalised CD ligands and their metal complexes. By using 6-O-tosyl-β-cyclodextrin, two phosphine ligands CDP and CDNP were synthesized. Two polydentate ligands CDNNP and CD3NP were also prepared starting from 6-(2-aminoethyl)-amino-6-deoxy-β-cylcodextrin. In order to mimic metalloenzymes, several transition metal complexes were prepared as well, including [PtCl(CDNNP)]+, [PdCl(CDNNP)]+, and [Pd(CDNNP)(η1-allyl)]+Cl-. In the other part of this thesis, we investigated the reactions of terminal acetylenes with M(PCP). The vinylidene complex OsCl(=C=CHR)(PPh3)(PCP) has been isolated from the reactions of OsCl(PPh3)(PCP) with terminal acetylenes. However, the vinylidene complexes do not undergo coupling reactions, but react with water to form carbyne complexes. In the case of rhodium, reaction of 1,3- (PPh2CH2)2C6H4 (PCHP) with [RhCl(COD)]2 in isopropanol produced a mixture of bimetallic complexes [RhCl(COD)]2(μ2-PCHP), RhH(PCP)(μ-Cl)2Rh(COD) and [RhHCl(PCP)]2(μ2-PCHP). Reaction of RhH(PCP)(μ-Cl)2Rh(COD) with CCl4 or CHCl3 produced RhCl(PCP)(μ-Cl)2Rh(COD). Except RhHCl(PCP)]2(μ2-PCHP), all the bimetallic complexes are catalytically active for polymerization of phenylacetylene. It is interesting to note that very different products were obtained from the reactions of terminal acetylenes with M(PCP) complexes. Ruthenium complexes would produce coupling products, osmium complexes would produce vinylidene complexes, while rhodium complexes would lead to the polymerization of acetylenes.
Note Thesis (M.Phil.)--Hong Kong University of Science and Technology, 1997
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Language English
Format Thesis
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