Date of Award
Master of Science (MS)
Sean E. Hightower
Coordination of the 2,6-bis(8′-quinolinyl)pyridine (bqp) ligand to a cobalt (Co) core and its influence to electron spin and configuration on the structures and properties of the resulting complexes has been investigated. The homoleptic complexes [Co(mer-bqp-κ3N,N′,N″)2][PF6]2Â (1) and [Co(mer-bqp-κ3N,N′,N″)2][Br3]3Â (2) were prepared and characterized. X-ray structure determinations of complexesÂ 1Â andÂ 2Â revealed twisted, near-octahedral arrangements relative to the cobalt center. The magnetic data forÂ 1Â is typical of those for distorted octahedral (i.e.,Â D4hÂ symmetry) high-spin d7Â species despite the near-ideal octahedral coordination of theÂ bqpÂ ligand around the Co(II) core. Electronic spectra forÂ 1Â andÂ 2Â have been investigated and assigned. Both complexes exhibit intense π–π∗ bqpÂ ligand centered transitions in the UV region and low intensity mixed charge transfer transitions in the visible region. Neither complex strongly absorbs in visible spectral region. The electrochemistry of these compounds has been studied and compared to that of similar cobalt terpyridine compounds. A metal-centered Co2+/3+Â redox wave and ligand-based reduction processes were observed forÂ 1Â andÂ 2Â in acetonitrile. The metal-centered redox potentials were reversible with potentials more positive than comparable cobalt-terpyridine complexes. Density functional theory (DFT) calculations of the electronic and ground state properties are in good agreement with the experimental data.
Frenzel, Blaise, "Characterization Of Newly Synthesized Cobalt Polypyridine Complexes Using NMR, X-Ray, Electrochemistry, And UV-Vis" (2015). Theses and Dissertations. 1771.