Kadish, Karl M.2014-04-052014-04-05December 22013-12http://hdl.handle.net/10657/592This thesis presents UV-visible, electrochemical, and spectroelectrochemical studies carried out in non-aqueous media of homo/heterobimetallic pyrazinoporphyrazine compounds, i.e.[(M′Cl2)LM] and [(PtCl2)(CH3)6LM](I)6, where L =tetrakis-2,3-[5,6-di(2-pyridyl)pyrazino]porphyrazinato anion,M =ZnII, MgII(H2O) or PdII and M′ =PdII or PtII, 2,3-di(2-pyridyl)-6,7-dicyano-1,4-quinoxaline, [(CN)2Py2Quin], its complexes [(CN)2Py2QuinMCl2] (M = PdII, PtII) and related pyrazine derivatives. The [(M′Cl2)LM] compounds, as obtained from the mononuclear species [LM], undergo only subtle UV-visible spectral changes and exhibit practically unchanged half-wave potentials for reduction; thus, peripheral coordination to the [LM] macrocycles of a single PdCl2 or PtCl2 unit at one of the external dipyridinopyrazine fragments only minimally disturbs the s/pelectronic distribution within the entire porphyrazine unit. In contrast, quaternization by CH3I of the six unligated pyridine N atoms of the species [(PtCl2)LM] leading to formation of the hexacations [(PtCl2)(CH3)6LM]6+results in a significant bathochromic shift (5–15 nm) of the Q-band positions, thus suggesting an enhanced electron-withdrawing effect determined by an incremented displacement of the s/pelectronic system towards the periphery of the macrocycle. Accordingly, there is a facilitated thermodynamic uptake of electrons upon going from [(PtCl2)(CH3)6LM]6+ to [(PtCl2)(CH3)6LM]n(n =5+ →2+). Noteworthy, the UV-visible spectra of the salt-like species [(PtCl2)(CH3)6LM](I)6in water at c =5 ×10-5M) indicate the presence of a monomer-dimer equilibrium, persistent even at very low concentrations (ca. 5 ×10-7M). The newly examined triad of neutral quinoxaline compounds and their corresponding pyrazine counterparts, demonstrated that the one-electron reduction of these compounds in nonaqueous solvents generally resulted in a bathochromic shift of bands in the 250-400 nm region of the spectrum, accompanied by the formation of intense additional absorptions in the region of 500-900 nm. These spectral bands of the monoanions are theoretically examined in the present study by TDDFT calculations and interpreted in terms of single electron excitations between the Kohn-Sham orbitals of the gas-phase optimized structures.application/pdfengThe author of this work is the copyright owner. UH Libraries and the Texas Digital Library have their permission to store and provide access to this work. Further transmission, reproduction, or presentation of this work is prohibited except with permission of the author(s).ElectrochemistryCyclic voltammetryPorphyrazinesPyrazineQuinoxalineSpectroelectrochemistryDFTTDDFTUV-visibleChemistry, Physical and theoretical2014-04-05Thesisborn digital