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Title: The Synthesis and Organometallic Chemistry of NonamethyIfluorene
Author: Moss, James Edward
Awarding Body: University of Oxford
Current Institution: University of Oxford
Date of Award: 2007
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Abstract:
The focus of this thesis is the synthesis and organometallic chemistry of the nonamethylfluorene ligand (Flu*). Chapter One summarises the properties and uses of the fluorene molecule and the incorporation of both the neutral and deprotonated forms of the ligand into organometallic complexes. The chapter concludes with a discussion of the properties that are bestowed upon organometallic compounds containing fully methylated ligands, detailing the need for nonamethylfluorene. Chapter Two describes a relatively high yielding total synthesis of the fully methylated fluorene, Flu*H, using techniques and equipment that are amenable to most laboratories. All but one of the precursors have been crystallographically characterised, and this analysis shows in all cases a twisted fluorene skeleton due to unfavourable close contacts between methyl groups. Octamethyldibenzofulvene has been radically coupled to form an ethane bridged ligand set using a technique not previously used for fluorene. Chapter Three documents the interaction of the neutral polymethylated fluorenes Flu*H and Flu'H with Cr, Fe and Mn. Both mono and bimetallic complexes have been isolated, and many have been crystallographically characterised. In the monometallic case, haptotropic shifts are seen for both Fe and Cr, but deprotonation of the Mn complex yields a previously unknown coordination mode of fluorene. DFT studies of the protonated and deprotonated bimetallic Cr complexes give an indication of the mode of metal-ligand binding, and this is confirmed by a crystallographic study. Bimetallic Fe complexes have been shown to be active catalysts in the dechlorination of PCBs, toxic environmental pollutants. Chapter Four describes the synthesis of Flu* transfer reagents; the crystal structure of the lithiate Flu*Li.TMEDA has been determined and shows a twisted fluorene skeleton. DFT studies on both the protonated and deprotonated, methylated and nonmethylated fluorenes have been performed to examine the distribution of charge in these molecules. Chapter Five discusses the interaction of the transfer reagents described in Chapter Four with a variety of metal precursors. Reasons for the observed lack of stability of Flu* containing complexes are given. The synthesis and molecular structure of complexes of Zr and In are reported; the Zr compound represents the first crystallographically characterised mono-fluorenyl Zr complex not containing a supporting heteroatom. The interaction of EBFlu*2- with metal precursors is also examined. Chapter Six describes the synthesis of mono and bimetallic Co complexes of octamethylfluorenone. Crystal structure determinations show that the Cp*Co fragment dearomatises both six membered rings in the fluorenone, only the second example ofthis type ofcoordination. Chapter Seven contains experimental procedures, Chapter Eight details characterising data for all new compounds, and crystallographic data in the form of CIF files may be found in the electronic Appendix, found on the compact disc at the back of this thesis.
Supervisor: Not available Sponsor: Not available
Qualification Name: University of Oxford, 2007 Qualification Level: Doctoral
EThOS ID: uk.bl.ethos.491509  DOI: Not available
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