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Titanacyclobutene and Cobalt(II) Phosphinimide Complexes
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- Author / Creator
- Gauthier, Jeremy M.
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This dissertation describes some advances that were made in the field of paramagnetic first-row transition metal complexes. Two independent topics will be discussed.
The first topic that will be discussed is the preparation and reactivity of titanacylobutene complexes. Initially, the Stryker group discovered that titanacyclobutenes can be prepared by the SmI2-mediated coupling of propargyl halides, [Cp2TiCl]2, and alkyl halides. We have since improved on this procedure; this involves replacing [Cp2TiCl]2 with titanocene(IV) dichloride, and replacing SmI2 with activated manganese powder. These conditions now give chemists the ability to prepare titanacyclobutenes from reagents that do not have to be kept under an inert atmosphere.
The second part of this topic discusses the conversion of titanacyclobutenes into 5-membered α-iminoenamine carbocycles. Iit has been demonstrated that titanacyclobutenes undergo double-insertion reactions with organic isonitriles which form carbocyclic-titanium enediamidate complexes however, successful reaction conditions for obtaining the titanium-free 5-membered carbocycles were unknown. We now report that 5-membered α-iminoenamine carbocycles can be obtained from carbocyclic-titanium enediamidate complexes through protonation, using 2,4,6-collidine hydrochloride.
The last part of this topic discusses our attempts to prepare titanacyclobutenes from titanium(IV) precursors which contain alternative ligands than cyclopentadienyl ligands. Trialkyl-phosphoranimide and diphenyl-sulfimide ligands are ideal candidates for this chemistry, because the imide nitrogen of both ligands acts as a six-electron donor to the titanium(IV) center and the alkyl or aryl substituents provide suitable steric shielding to the metal center. This section discusses both the preparation and reactivity of three precursors: ((t-bu)3PN)2TiCl2, Cp(Ph2SN)TiCl2 and Cp*(Ph2SN)TiCl2.
The second half of this document discusses our attempts to prepare late transition metal phosphinimide complexes; we were particularly interested in preparing analogues of cobaltocene (Cp2Co) and half-sandwich cobalt(I) (CpCo) analogues. A series of new cobalt(II) phosphinimide complexes were prepared by the addition of lithium di(i-propyl)amide (LDA) to cobalt(II) phosphinimine coordination complexes. Continuing studies in this area revealed that cobalt(II) phosphinimide complexes are reactive towards electrophilic and acidic compounds; this led to the isolation of other new cobalt(II) phosphinimide clusters and cobalt(II) phosphinimine complexes. -
- Graduation date
- Fall 2012
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- Type of Item
- Thesis
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- Degree
- Doctor of Philosophy
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- License
- This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.