Physical Sciences and Mathematics Commons^™

Computational Study Of The Reactions Of Heteroatomic Compounds On Ceo2, Suman Bhasker Ranganath

LSU Doctoral Dissertations

The mechanisms of ambient-temperature reactions of heteroatomic compounds catalyzed by ceria (CeO₂), an archetypical reducible oxide, for enzyme mimetics, environmental protection, and chemical synthesis are investigated in this dissertation using theoretical methods. CeO₂ is modeled with thermodynamically stable low-index surfaces exposed by commonly studied ceria thin films and nano particles. To understand phosphatase-like dephosphorylation activity, stable adsorption states and surface reactions of model phosphates are examined. Binding of the central P-atom to surface lattice oxygen (O_latt) supplemented by phosphoryl O-Ce interaction is the only stable adsorption state for the un-dissociated molecule. Deprotonation of phosphate monoesters, …

Improved Synthesis, Separation, Transition Metal Coordination And Reaction Chemistry Of A New Binucleating Tetraphosphine Ligand, Ekaterina Kalachnikova

LSU Doctoral Dissertations

The first chapter of this dissertation involves discussion of alkene hydration and oxidative cleavage reactions catalyzed by late transition metal complexes. Previously reported results are summarized here. Mechanistic aspects of alkene hydration catalyzed by late transition metal complexes are also explained. The second part of Chapter 1 focuses on motivation for using bimetallic nickel phosphine complexes as possible catalytic precursors for alkene hydration. Chapter 2 describes studies into alkene hydration in the presence of catalytic amounts of dinickel phosphine complexes based on linear tetraphosphine ligand, PEt2CH2CH2(Ph)PCH2P(Ph)CH2CH2PEt2, et,ph-P4. Under conditions tested no alcohol products were detected. However we have observed formation …

Investigations Into Alkene Hydration And Alkene Oxidation Catalysis, William Schreiter

LSU Doctoral Dissertations

Bimetallic Ni complexes Ni21M and Ni21R and monometallic transition metal complexes were investigated as possible alkene hydration catalysts under a multitude of different reaction conditions. All attempts at performing this catalytic reaction failed to give any alcohol products. Catalytic screening experiments were conducted using a mixture of racemic-et,ph-P4 and meso-et,ph-P4, 1M and 1R, and various transition metals. These experiments gave several different products including 1-phenylethanol from styrene. During the course of the hydration experiments, an aldehyde product was identified from experiments conducted with the bimetallic complexes in air. Experiments have shown that the aldehyde is produced from the oxidative cleavage …

Toward The Advancement Of Tetraphosphine Ligand Synthesis For Homogeneous Bimetallic Catalysis, Marc Anthony Peterson

LSU Doctoral Dissertations

A tetraphosphine ligand rac-et,ph-P4 (Et2PCH2CH2(Ph)PCH2P(Ph)CH2CH2PEt2) is used for the formation of a highly active and regioselective bimetallic hydroformylation catalyst. The proposed active catalytic species in acetone, [Rh2H2(µ-CO)2(rac-et,ph- P4)]2+, is formed in situ under H2/CO pressure. This is one of the most impressive examples of cooperativity in homogeneous catalysis. The fragmentation of this catalyst by CO has been investigated and confirmed by in situ NMR spectroscopic studies. A new tetraphosphine ligand rac-et,ph-P4-Ph (et,ph-P4-Ph = Et2P(o-C6H4)P(Ph)CH2(Ph)P(o-C6H4)PEt2) has been synthesized to combat this fragmentation problem. However, the inability to successfully separate the meso and racemic diastereomers led to the attempted alteration of the …

Studies Of A Dirhodium Tetraphosphine Catalyst For Hydroformylation And Aldehyde-Water Shift Catalysis, Aaron Rider Barnum

LSU Doctoral Dissertations

Research into the dirhodium tetraphosphine catalyst precursor [rac-Rh2(nbd)2(et,ph-P4)](BF4)2 shows it is capable of forming a highly active and regioselective hydroformylation catalyst in situ when using an acetone or acetone/water solvent. Hydroformylation experiments (using 1-hexene), FT-IR studies, and acid-base studies were performed to better understand the various complexes of the dirhodium catalyst cycle. These studies lead to the newly proposed catalyst mechanism when performed in an acetone/water solution, using the monocationic [rac-Rh2(H)(µ-CO)2(CO) (et,ph-P4)]+ as the proposed active catalyst complex for hydroformylation. For the conversion of 1-hexene to heptanal, it is capable of performing an initial rate of 30 turnovers per min, …

Separation And In Situ Catalytic Testing Of A Dirhodium Tetraphosphine Catalyst, Bobby Lloyd Barker

LSU Doctoral Dissertations

Attempts to study the asymmetric hydroformylation abilities of [rac-Rh₂(nbd)₂(et,ph-P4)](BF₄)₂ were made through the separation of the enantiomers of et,ph-P4 using a chiral HPLC column. Efforts were also made to optimize the NiCl₂ separation chemistry for the methyl analogue of et,ph-P4 for use in asymmetric hydroformylation. A study of hydroformylation of olefins using [rac-Rh₂(nbd)₂(et,ph-P4)](BF₄)₂ in ionic liquids was also performed, leading directly to the important (and unexpected) effect of increased hydrogen pressure on [rac-Rh₂(nbd)₂(et,ph-P4)](BF₄)₂ in the acetone/water system to …

Electronic Structural Investigations Of Bi- And Polymetallic Complexes Using Quantum Mechanical Methods, Zakiya Sheni Wilson

LSU Doctoral Dissertations

Understanding the dynamics influencing chemical reactivity is essential for properly exploiting matter into more useful purposes. In that manner, computational chemistry is a tool frequently used to study chemical properties at the most intimate level, i.e. the single molecule.

With this work, we probe the chemistry governing a variety of multi-faceted bi- and polymetallic compounds. To date our research consists of four major projects: bimetallic rhodium-catalyzed hydroformylation and aldehyde-water shift hydrocarboxylation catalysis; a novel linear M-H-M interaction in a bridged bis(dialkylphosphino)methane complex of nickel; and CeBe₁₃, a heavy fermion conductor. Computational investigations on these systems allow us to …