Browsing by Author "Vlaisavljevich, Bess"

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    Quantum chemical studies of actinides and lanthanides: from small molecules to nanoclusters
    (2013-06) Vlaisavljevich, Bess
    Research into actinides is of high interest because of their potential applications as an energy source and for the environmental implications therein. Global concern has arisen since the development of the actinide concept in the 1940s led to the industrial scale use of the commercial nuclear energy cycle and nuclear weapons production. Large quantities of waste have been generated from these processes inspiring efforts to address fundamental questions in actinide science. In this regard, the objective of this work is to use theory to provide insight and predictions into actinide chemistry, where experimental work is extremely challenging because of the intrinsic difficulties of the experiments themselves and the safety issues associated with this type of chemistry. This thesis is a collection of theoretical studies of actinide chemistry falling into three categories: quantum chemical and matrix isolation studies of small molecules, the electronic structure of organoactinide systems, and uranyl peroxide nanoclusters and other solid state actinide compounds. The work herein not only spans a wide range of systems size but also investigates a range of chemical problems. Various quantum chemical approaches have been employed. Wave function-based methods have been used to study the electronic structure of actinide containing molecules of small to middle-size. Among these methods, the complete active space self consistent field (CASSCF) approach with corrections from second-order perturbation theory (CASPT2), the generalized active space SCF (GASSCF) approach, and Møller-Plesset second-order perturbation theory (MP2) have been employed. Likewise, density functional theory (DFT) has been used along with analysis tools like bond energy decomposition, bond orders, and Bader's Atoms in Molecules. From these quantum chemical results, comparison with experimentally obtained structures and spectra are made.
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    Supporting Information for Ligand effects on Decarbonylation of Palladium-acyl Complexes
    (2020-10-22) Wiessner, Tedd C; Fosu, Samuel A; Parveen, Riffat; Vlaisavljevich, Bess; Tolman, William B; Rath, Nigam; wbtolman@wustl.edu; William, Tolman; University of South Dakota, Vlaisavljevich Lab; Washington University in Saint Louis, Tolman Lab, Department of Chemistry and Center for Sustainable Polymers
    These files contain primary data along with associated output from instrumentation supporting all results reported in "Ligand effects on Decarbonylation of Palladium-acyl Complexes". In this work we found: The influences of perturbations of supporting phosphine ligands on the dehydrative decarbonylation of (Ln)Pd(II)(Cl)-hydrocinnamoyl com-plexes (L = PtBu3, n = 1; L = PPh3, n = 2; L = dppe, n = 1) to yield styrene were studied through combined experiment and theory. Abstraction of chloride from the complexes by silver and zinc salts, as well as sodium tetrakis[3,5-bis(trifluoromethyl)phenyl]borate, enhanced the efficiency of styrene formation, according to the trend in L: PtBu3 > dppe > PPh3. DFT calculations corroborated the experimental findings and provided insights into the ligand influences on reaction step barriers and transition state structures. Key findings include: a stable intermediate forms after chloride abstraction, from which -hydride elimination is rate-determining, the low coordination number for the PtBu3 case lowers reaction barriers for all steps, and the trans disposition of two ligands for L = PPh3 contributes to low efficiency for styrene production in that case.