Thesis (Ph. D.)--University of Canterbury, 2008. / Typescript (photocopy). "March 2008." Includes bibliographical references (leaves 217-225). Also available via the World Wide Web.

Honors Project--Smith College, Northampton, Mass., 2010. / Includes bibliographical references.

<p dir="ltr">The use of redox non-innocent ligands to imbue third-row transition metal complexes with properties emulating those of their fourth- and fifth-row congeners has become an attractive strategy to overcome the limited resources and environmental implications associated with the latter class of metals. The tetra-imine macrocycle, TIM (2,3,9,10-tetramethyl-1,4,8,11-tetraza-cyclotetradeca-1,3,8,10-tetraene), which bears two sets of potentially redox-active α-diimine units, therefore, has been targeted as the ligand scaffold to investigate the structural and electronic properties of various organocobalt(III) complexes within this work.</p><p dir="ltr">First, the reaction between <i>trans</i>-[Co(TIM)Cl₂]⁺ and terminal alkynes (HC₂Ar), in the presence of triethylamine, yielded a series of mono- and bis-alkynyl Co^III(TIM) complexes, as discussed in Chapters 1 and 2. Interestingly, the use of electron-rich terminal alkynes (HC₂Y) favors the formation of products featuring a 1-aza-2-cobalt-cyclobutene unit. As detailed in Chapter 3, the <i>trans</i>-[Co(TIM')(HC=C)Y)Cl]⁺-type complexes (TIM' = the resulting derivative of TIM) were prepared through the addition of HC₂Y to <i>trans</i>-[Co(TIM)Cl₂]⁺ in the presence of KOH. The unprecedented involvement of the TIM ligand was verified crystallographically and through ¹H NMR and FT-IR spectroscopies. In Chapter 4, the properties and influences of the aza-cobalt-cyclobutene are further explored through UV-vis spectroelectrochemical studies on the constitutional isomers, <i>trans</i>-[Co(TIM)(C₂Fc)Cl]⁺ and <i>trans</i>-[Co(TIM')((HC=C)Fc)Cl]⁺ (Fc = ferrocene). Moreover, the reactivity of the Co^III center in the latter complexes is investigated via the reaction with KCN and AgOTf in CH₃CN.</p><p dir="ltr">In Chapter 5, a new facet of Co^III(TIM) reactivity is revealed through the reaction between <i>trans</i>-[Co(TIM)Cl₂]⁺ and HC₂Ar, in the presence of NaBH₄. The reaction generates both mono- and bis-alkenyl complexes along with products containing a 1-aza-2-cobalt-cyclopropane unit. The formation of the former class of products is postulated to proceed through a transient H-Co^III(TIM) intermediate, while the latter is believed to be accessed upon the reduction of an imine moiety within the TIM ligand. Moreover, the generation of the three-membered ring showcases another example of the non-innocent nature of the TIM ligand.</p>

The FT-Raman techniques were developed to quantify reactions that follow on mixing aqueous solutions of bis-(1,3-diaminopropane)diaquacobalt( III) ion ([Co(tn)2(0H)(H20)]2+) and p-nitrophenylphosphate (PNPP). For the development and validation of the kinetic modelling technique, the well-studied inversion of sucrose was utilized. Rate constants and concentrations could be estimated using calibration solutions and modelling methods. It was found that the results obtained are comparable to literature values. Hence this technique could be further used for the [Co(tn)2(0H)(H20)]2+ assisted hydrolysis of PNPP. It was found that rate constants where the pH is maintained at 7.30 give results which differ from those where the pH is started at 7.30 and allowed to change during the reaction. The average rate constant for 2:1 ([Co(tn)2(0H)(H20)]2+:PNPP reactions was found to be approximately 3 x 104 times the unassisted PNPP hydrolysis rate. / Chemistry / M. Sc. (Chemistry)