This thesis is concerned with the synthesis and properties of fluorocarbene complexes of ruthenium and osmium. Chapter 1 is a review of transition metal CF3-complexes and illustrates a number of unusual features of these compounds which makes them suitable for modification into CF2-complexes. To place the fluorocarbene complexes into context, Chapter 2 contains a brief review of transition metal carbene complexes with the emphasis on other halocarbene species. As described in Chapter 3, CF3-complexes of ruthenium can be prepared by the addition of Hg(CF3)2 to Ru(CO)3(PPh3)2. The x-ray crystal structure of Ru(HgCF3)(CF3)(CO)2(PPh3)2 shows longer C-F bonds in the ruthenium bound CF3-group than in the mercury bound CF3-group. Reactions of fluorocarbon complexes with Lewis acids have been explored and RuCl(CF3)(CO)2(PPh3)2 reacts with BCl3 to form the known RuCl2(CO)(CCl2)(PPh3)2. Similarly OsCl(CF2H)(CO)2(PPh3)2 reacts with one equivalent of BCl3 to form initially a cationic carbene complex in which the carbene carbon atom substitutes first into a benzene ring of one PPh3-ligand and, through further reaction with BCl3, into a ring of the second PPh3-ligand. The x-ray crystal structures of OsCl(CO)2(PPh2C6H4CHCl)PPh3 and OsCl(CO)2(PPh2C6H4CH)(PPh2C6H4) are reported. RuCl(CF3)(CO)2(PPh3)2 in many of its reactions behaves as a CF2-complex precursor and Chapter 4 describes the reaction between the related RuCl(CF3)(CH3CN)(CO)(PPh3)2 and Me3SiCl to form the first isolable CF2-complex, RuCl2(CO)(CF2)(PPh3)2. RuCl2(CO)(CF2)(PPh3)2 contains an electrophilic carbene ligand and reacts rapidly with hard, oxygen and nitrogen containing nucleophiles. A comparison of the reactivity of RuCl2(CO)(CF2)(PPh3)2 and RuCl2(CO)(CCl2)(PPh3)2 is presented and reasons for the differing reactivities proposed. Chapter 5 shows that d8 CF2-complexes can be prepared directly from reaction between the more active CF3-transfer reagent, Cd(CF3)2-glyme, and various zerovalent complexes. The x-ray crystal structures of M(CO)2(CF2)(PPh3)2 M = Ru, Os and OsCl(NO)(CF2)(PPh3)2 are described and the bonding characteristics of the CF2-ligand discussed. The carbene ligand of M(CO)2(CF2)(PPh3)2 M = Ru, Os has some nucleophilic character and reacts readily with electrophiles, for example reaction with HC1 yields MCl(CF2H)(CO)2(PPh3)2 M = Ru, Os. A comparison between RuCl2(CO)(CF2)(PPh3)2 and Ru(CO)2(CF2)(PPh3)2 reveals that the reactivity of the carbene ligand is controlled by the electron density at the metal centre, i.e. is oxidation state dependent.
| Identifer | oai:union.ndltd.org:ADTP/276028 |
| Date | January 1983 |
| Creators | Hoskins, S. V. |
| Publisher | ResearchSpace@Auckland |
| Source Sets | Australiasian Digital Theses Program |
| Language | English |
| Detected Language | English |
| Rights | Items in ResearchSpace are protected by copyright, with all rights reserved, unless otherwise indicated., http://researchspace.auckland.ac.nz/docs/uoa-docs/rights.htm, Copyright: The author |
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