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DC Field | Value | Language |
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dc.contributor.advisor | McGlinchey, M.J. | en_US |
dc.contributor.author | Decken, Andreas | en_US |
dc.date.accessioned | 2014-06-18T16:43:42Z | - |
dc.date.available | 2014-06-18T16:43:42Z | - |
dc.date.created | 2011-01-29 | en_US |
dc.date.issued | 1993-08 | en_US |
dc.identifier.other | opendissertations/3879 | en_US |
dc.identifier.other | 4896 | en_US |
dc.identifier.other | 1750412 | en_US |
dc.identifier.uri | http://hdl.handle.net/11375/8694 | - |
dc.description.abstract | <p>Transition-metal complexes of the tetracyclic system 4H-cyclopenta[def]phenanthrene (cppH) have been prepared for a series of metals, i.e. (η⁶-cppH)Cr(CO)₃, (η⁶-cppH)Mn(CO)₃⁺ and (η⁶-cppH)Fe(C₅H₅)⁺; in all cases the metal is bonded to a terminal six-membered ring. Upon deprotonation, the corresponding (η⁶-cpp) species can be trapped at low temperatures. Raising the temperature results in a η⁶- to η⁵-haptotropic shift, in the case of the Cr(CO)₃ complex at temperatures above -30℃ and +20℃ for the Mn(CO)₃ complex. However, heating of a sample of (η⁶-cpp)Fe(C₅H₅) did not result in a haptotropic rearrangement. The corresponding 8,9-dihydro-cpp derivatives (η⁶-H₂-cppH)Cr(CO)₃ and [(η⁶-H₂cppH)Mn(CO)₃] PF₆ have also been prepared. Deprotonation of the Mn(CO)₃ complex yielded the thermally stable compound (η⁶-H₂ccp)Mn(CO)₃ which only undergoes an η⁶- to η⁵-haptotropic shift upon heating to 60℃ for one hour. The relative ease of haptotropic shifts in the cpp complexes can be rationalized in terms of a transition state in which the migrating organometallic fragment is η³-bonded to the polycyclic ligand in which a 10π (naphthalene like) system is retained. EHMO calculations predict that the barriers to migration in case of the (cpp)FeCp system can be expected to be some 4.5 kcal mol⁻¹ lower than in the corresponding fluorenide system. Furthermore, calculations for the system (cpp)Mn(CO)₃ reveal that the barriers to migration can be expected to be much lower than in the analogous (cpp)Fe(C₅H₅) system. The barriers were calculated to be 17.5 kcal mol⁻¹ and 30.0 kcal mol⁻¹ respectively. Reactions have been carried out to prove the existence of the proposed η³-transition state. In the course of these studies, the complexes (η¹-cpp)Fe(C₅H₅) and (η¹-cpp)Mn(CO)₃(P(C₂H₅)₃)₂ have been synthesized, both of which were found to be unexpectedly stable.</p> | en_US |
dc.subject | Chemistry | en_US |
dc.subject | Chemistry | en_US |
dc.title | Haptotropic rearrangements in metal complexes of 4H-cyclopenta(def)phenanthrene | en_US |
dc.type | thesis | en_US |
dc.contributor.department | Chemistry | en_US |
dc.description.degree | Doctor of Philosophy (PhD) | en_US |
Appears in Collections: | Open Access Dissertations and Theses |
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fulltext.pdf | 3.45 MB | Adobe PDF | View/Open |
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