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Texas A&M University
1.
Chupik, Rachel Beth.
Developments in the Understanding of the Dinitrosyl Iron Unit: Its Stabilization, Reactivity, and Nitric Oxide Release.
Degree: PhD, Chemistry, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/173248 
► Dinitrosyl iron complexes (DNICs), as well as S-nitrosothiols (RSNOs), form endogenously to provide a stable means of storage and transport for the highly reactive signaling…
(more)
▼ Dinitrosyl iron complexes (DNICs), as well as S-nitrosothiols (RSNOs), form endogenously to provide a stable means of storage and transport for the highly reactive signaling molecule, nitric oxide. Through the development of biomimetic complexes, the fundamental chemistry of such DNICs is established within a range of ligand sets as anionic and neutral donors that stabilize the dinitrosyl iron unit, DNIU, in oxidized {Fe(NO)₂}⁹ and reduced {Fe(NO)₂}¹⁰ (Enemark-Feltham notation) redox levels. This amorphous electronic characteristic is readily accommodated by amino acid residues, cysteinyl S- and histidine N-donors, and their surrogates, as ligands to iron. My research targets a greater understanding of DNIC reactivity with components of cellular environments, the possible connections between the electronically similar d⁹ , Cu(II) and d¹⁰, Cu(I), redox couple, the DNIC/Copper/RSNO connections, structural studies of aggregates of DNICs with metallodithiolates, as well as design strategies for NO-release therapeutic development of DNICs.
A stable, reduced, {Fe(NO)₂}¹⁰ DNIC containing a bipyridyl ligand, [(neo)Fe(NO)₂] (neo = 2,9-dimethyl-1,10-phenanthroline) was used to explore redox switches and N₂ ligand exchange between copper and the Fe(NO)₂. Both Cu^I and Cu^II sources were found to promote neo ligand transfer from the DNIU with concomitant NO release. With Cu^II, redox processes were also involved, as evidenced by the formation of a mixture of oxidized {Fe(NO)₂}⁹ DNICs, in addition to both Cu^I- and Cu^II-neo complexes. Copper is known to catalyze the release of NO from RSNOs, and our discoveries found here are the first biomimetic investigation of copper’s reactivity with DNICs.
Reaction of an RSNO with reduced, {Fe(NO)₂}¹⁰ DNICs, [(L)₂Fe(NO)₂] (L = CO or neo), results in NO release and the formation of a unique (-S)(SR)₂[Fe(NO)₂]₄ cluster, containing an interstitial sulfide. Such a cluster can be visualized as a plausible intermediate in the known conversion of DNICs to FeS clusters. The NO released showed complete scrambling with ¹⁵N-labeled RSNO.
Although DNICs are promising NO-delivery candidates, the lack of biocompatible examples has hindered their development into useful therapeutics. We reported the first DNICs with pendant thiosugars, isolated in both monomeric and dimeric form. Cytotoxicity towards endothelial cells was low and steady NO release over several hours was observed in aqueous media.
Advisors/Committee Members: Darensbourg, Marcetta Y (advisor), Lindahl, Paul (committee member), Nippe, Michael (committee member), Villalobos, Alice Y. (committee member).
Subjects/Keywords: Dinitrosyl iron unit; dinitrosyl iron complex; DNIC; nitric oxide
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APA (6th Edition):
Chupik, R. B. (2017). Developments in the Understanding of the Dinitrosyl Iron Unit: Its Stabilization, Reactivity, and Nitric Oxide Release. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/173248
Chicago Manual of Style (16th Edition):
Chupik, Rachel Beth. “Developments in the Understanding of the Dinitrosyl Iron Unit: Its Stabilization, Reactivity, and Nitric Oxide Release.” 2017. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/173248.
MLA Handbook (7th Edition):
Chupik, Rachel Beth. “Developments in the Understanding of the Dinitrosyl Iron Unit: Its Stabilization, Reactivity, and Nitric Oxide Release.” 2017. Web. 01 Mar 2021.
Vancouver:
Chupik RB. Developments in the Understanding of the Dinitrosyl Iron Unit: Its Stabilization, Reactivity, and Nitric Oxide Release. [Internet] [Doctoral dissertation]. Texas A&M University; 2017. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/173248.
Council of Science Editors:
Chupik RB. Developments in the Understanding of the Dinitrosyl Iron Unit: Its Stabilization, Reactivity, and Nitric Oxide Release. [Doctoral Dissertation]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/173248
Texas A&M University
2.
Lunsford, Allen Michael.
Bridging Thiolates in Metalloenzymes: From Model Complexes to Catalytic Small Molecule Activation.
Degree: PhD, Chemistry, 2016, Texas A&M University
URL: http://hdl.handle.net/1969.1/174288
► The discovery of cyano-iron carbonyls in the hydrogenases has inspired synthetic efforts to reproduce the active sites of these efficient H2-producing or H2-oxidation enzymes. Recent…
(more)
▼ The discovery of cyano-iron carbonyls in the hydrogenases has inspired synthetic efforts to reproduce the active sites of these efficient H2-producing or H2-oxidation enzymes. Recent demonstration of the possibility of loading apo-HydA ([FeFe]-H2ase enzyme) and apo-HydF (maturase protein) with synthetic analogues of the active site provides evidence that small molecular models are indeed the essential catalyst.
Interrogation by EPR spectroscopy of the biohybrids indicate a role for the cyanide in attaching the organometallic unit to a carrier protein; in fact, the cyanide has flipped from its origin in the synthetic diiron unit and inserts into the maturation protein, HydF, resulting in a 4Fe4S docking of the diiron model complex, but placing the cyanide nitrogen next to the 2Fe site. In order to probe the requirements for such cyanide isomerization, we have prepared cyanide-bridged constructs of 3-Fe systems with features related to the organoiron moiety within the loaded HydF protein. The orientation of the CN bridge is determined by the precursors; no cyanide flipping was observed. Density function theory computations find a high barrier accounts for the kinetically controlled products.
In another study, complexes of formulation (µ-SCH2XCH2S)[Fe(CO)3]2, with X=CH2, CMe2, CEt2, NMe, NtBu, and NPh were determined to be photocatalysts for release of H2 gas from H3B←NHMe2. The thermal displacement of H3B←Net3 from photochemically generated (µ-SCH2XCH2S)[Fe(CO)3][Fe(CO)2(µ-H)(BH2-Net3)] by P(OEt)3 was monitored by time-resolved FTIR spectroscopy. Kinetic data reveals an associative mechanism for X=CH2 and dissociative mechanism for the alkylated and nitrogen bridgehead species. This allows us to rank the catalysts in terms of their B-H unit binding ability, a key step in the dehydrogenation process. The rate of H2 production from the initially formed (µ-SCH2XCH2S)[Fe(CO)3][Fe(CO)2(µ-H)(BH2-NHMe2)] complexes was inversely correlated with the lifetime of the analogous (μ-SCH2XCH2S)[Fe(CO)3][Fe(CO)2(µ-H)(BH2-Net3)] adducts.
Finally, a new series of complexes featuring MN2S2 metallodithiolates bound to Mn/Re(CO)3X were synthesized and characterized as electrocatalysts for C)2 reduction. Butterfly type structures resulted from binding of the lone pairs of the sulfur atoms to the Re/Mn(CO)3X unit. Under a CO2 atmosphere, there was a current enhancement in the cyclic voltammogram which is indicative of CO2 reduction to CO. Detailed electrochemical experiments are presented along with an appropriate characterization of catalytic processes using cyclic voltammetry and bulk electrolysis. Two complexes will be used as a case study.
Advisors/Committee Members: Darensbourg, Marcetta Y (advisor), Dunbar, Kim R (committee member), Nippe, Michael (committee member), Igumenova, Tatyana I (committee member).
Subjects/Keywords: Hydrogenase; Small Molecule Activation; Hydrogen; Organometallic
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APA (6th Edition):
Lunsford, A. M. (2016). Bridging Thiolates in Metalloenzymes: From Model Complexes to Catalytic Small Molecule Activation. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/174288
Chicago Manual of Style (16th Edition):
Lunsford, Allen Michael. “Bridging Thiolates in Metalloenzymes: From Model Complexes to Catalytic Small Molecule Activation.” 2016. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/174288.
MLA Handbook (7th Edition):
Lunsford, Allen Michael. “Bridging Thiolates in Metalloenzymes: From Model Complexes to Catalytic Small Molecule Activation.” 2016. Web. 01 Mar 2021.
Vancouver:
Lunsford AM. Bridging Thiolates in Metalloenzymes: From Model Complexes to Catalytic Small Molecule Activation. [Internet] [Doctoral dissertation]. Texas A&M University; 2016. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/174288.
Council of Science Editors:
Lunsford AM. Bridging Thiolates in Metalloenzymes: From Model Complexes to Catalytic Small Molecule Activation. [Doctoral Dissertation]. Texas A&M University; 2016. Available from: http://hdl.handle.net/1969.1/174288
Texas A&M University
3.
Park, Soomin.
Rhenium Tricarbonyl Complex Featuring Amine Moieties as Molecular Catalysts for Electrocatalytic CO2 Reduction.
Degree: MS, Chemistry, 2017, Texas A&M University
URL: http://hdl.handle.net/1969.1/161572
► Molecular catalysts for the electrochemical reduction of CO2 are being investigated for the potential utilization of CO2 as a viable C1 feedstock for the chemical…
(more)
▼ Molecular catalysts for the electrochemical reduction of CO2 are being investigated for the potential utilization of CO2 as a viable C1 feedstock for the chemical industry and energy economy. Various CO2 reduction products can be generated such as CO, CH3OH, and CH4. Among the several multi-electron reduction products, this study focuses on the proton-coupled, two-electron reduction of CO2 to generate selectively CO (and H2O as the byproduct).
Several examples of selective CO2 reduction electrocatalysts, such as Ni(cyclam)
2+, cobalt macrocyclic compounds based on azacalix[4](2,6)pyridines, and FeTDHPP (TDHPP = tetrakis(2',6'-dihydroxylphenyl)porphyrin), feature protic N-H or O-H groups in the vicinity of the reactive metal ion. Hydrogen-bonding like interactions between N-H groups and reduced CO2 intermediates are proposed to stabilize transition states in Ni(cyclam)
2+ and cobalt macrocyclic compound, and the O-H groups in FeTDHPP are found to increase catalytic activity by acting as local proton sources.
Inspired by these reports, this study examines the effects of the interactions from the secondary coordination sphere of well-studied Lehn-type catalyst systems for CO2 reduction. Lehn-type pre-catalysts feature Re(CO)3X (X = Cl, Br, and py) moieties coordinated to bipyridine or phenanthroline chelators and have been previously shown to be highly selective for CO2 reduction.
Advisors/Committee Members: Nippe, Michael (advisor), Darensbourg, Marcetta Y. (committee member), Powers, David C. (committee member), Wang, Haiyan (committee member).
Subjects/Keywords: Molecular catalyst; Electrocatalyst; CO2 reduction; Electrochemistry
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APA (6th Edition):
Park, S. (2017). Rhenium Tricarbonyl Complex Featuring Amine Moieties as Molecular Catalysts for Electrocatalytic CO2 Reduction. (Masters Thesis). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/161572
Chicago Manual of Style (16th Edition):
Park, Soomin. “Rhenium Tricarbonyl Complex Featuring Amine Moieties as Molecular Catalysts for Electrocatalytic CO2 Reduction.” 2017. Masters Thesis, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/161572.
MLA Handbook (7th Edition):
Park, Soomin. “Rhenium Tricarbonyl Complex Featuring Amine Moieties as Molecular Catalysts for Electrocatalytic CO2 Reduction.” 2017. Web. 01 Mar 2021.
Vancouver:
Park S. Rhenium Tricarbonyl Complex Featuring Amine Moieties as Molecular Catalysts for Electrocatalytic CO2 Reduction. [Internet] [Masters thesis]. Texas A&M University; 2017. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/161572.
Council of Science Editors:
Park S. Rhenium Tricarbonyl Complex Featuring Amine Moieties as Molecular Catalysts for Electrocatalytic CO2 Reduction. [Masters Thesis]. Texas A&M University; 2017. Available from: http://hdl.handle.net/1969.1/161572
Texas A&M University
4.
Cardenal, Ashley Danielle.
Towards Selective C-H Oxidation with Aerobically Generated Hypervalent Iodine Reagents.
Degree: PhD, Chemistry, 2019, Texas A&M University
URL: http://hdl.handle.net/1969.1/188714
► Enzymatic hydrocarbon oxidation allows for the selective late-stage functionalization of complex molecules by utilizing O2 as the terminal oxidant. We are interested in the development…
(more)
▼ Enzymatic hydrocarbon oxidation allows for the selective late-stage functionalization of complex molecules by utilizing O
2 as the terminal oxidant. We are interested in the development of abiological systems that enable functionalization of complex organic molecules using O
2 by utilizing metal-organic framework (MOF) catalysts to effect selective C–H oxidation and to combine this with the environmentally friendly generation of hypervalent iodine reagents, commonly used oxidants in MOF catalysis. To reach this long-term goal, there are fundamental studies that must be addressed. In order to access the pore space of a porous material for selective catalysis, the rates of substrate diffusion and catalytic reaction must be considered.
Thus, it is necessary to understand what is known of the diffusion processes relevant to porous materials and methods for probing the relative rates of catalytic reactions to diffusion. In this vein, we investigate the use of cis-decalin as a stereochemical probe for differentiating interstitial from interfacial catalysis for C–H oxidation reactions for porphyrinic metal-organic frameworks. In addition, we examine the effect particle size has on oxidation selectivity and further optimize reaction conditions for the selective oxidation of 1,4-cisdimethylcyclohexane by 2-D layered porphyrinic materials. Lastly, we initiate investigations of coupling the generation of hypervalent iodine chemistry with MOF catalysis by first analyzing the reactivity of hypervalent iodine reagents with soluble analogues of the metalloclusters that serve as secondary building units in MOFs.
Advisors/Committee Members: Powers, David C. (advisor), Wooley, Karen L. (committee member), Ozerov, Oleg V. (committee member), Nippe, Michael (committee member), Meek, Thomas D. (committee member).
Subjects/Keywords: C-H oxidation; MOF; catalysis; heterogeneous catalysis
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APA (6th Edition):
Cardenal, A. D. (2019). Towards Selective C-H Oxidation with Aerobically Generated Hypervalent Iodine Reagents. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/188714
Chicago Manual of Style (16th Edition):
Cardenal, Ashley Danielle. “Towards Selective C-H Oxidation with Aerobically Generated Hypervalent Iodine Reagents.” 2019. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/188714.
MLA Handbook (7th Edition):
Cardenal, Ashley Danielle. “Towards Selective C-H Oxidation with Aerobically Generated Hypervalent Iodine Reagents.” 2019. Web. 01 Mar 2021.
Vancouver:
Cardenal AD. Towards Selective C-H Oxidation with Aerobically Generated Hypervalent Iodine Reagents. [Internet] [Doctoral dissertation]. Texas A&M University; 2019. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/188714.
Council of Science Editors:
Cardenal AD. Towards Selective C-H Oxidation with Aerobically Generated Hypervalent Iodine Reagents. [Doctoral Dissertation]. Texas A&M University; 2019. Available from: http://hdl.handle.net/1969.1/188714
Texas A&M University
5.
Lo, Ying Hao.
Coordination and Redox Chemistry of Antimony-Based Ligands and Applications in Organometallic Catalysis.
Degree: PhD, Chemistry, 2019, Texas A&M University
URL: http://hdl.handle.net/1969.1/188767
► The use of Z-ligands to modulate the electronic property of transition metal centers is a powerful strategy in catalyst design. Our group has shown that…
(more)
▼ The use of Z-ligands to modulate the electronic property of transition metal centers is a powerful strategy in catalyst design. Our group has shown that antimony-based ambiphilic ligand, accept electron density from adjacent metal centers by the σ* orbital of the antimony (V) center and thus increasing the electrophilic reactivity of the trancition metal center. In this thesis, we were eager to determine if the charge of the Ztype ligand can be used to further enhance this effect. To this end, we synthesized a dicationic gold complex [46]
2+ ([(o‐(Phv2P)Cv6Hv4)v2(o‐Phv2PO)Cv6vHV4)SbAuCl]
2+) featuring a dicationic antimony (V) ligand with a phosphine oxide arm coordinating to the antimony center. Both experimental and computational results show that the gold complex possess a strong Au→Sb interaction reinforced by the dicationic character of the antimony center. The gold‐bound chloride anion of this complex is rather inert and necessitates the addition of excess AgNTfv2 to undergo activation. The activated complex, referred to as [47]
2+ ([((o‐(Phv2P)Cv6Hv4)v2(o‐Phv2PO)Cv6Hv4)SbAuNTfv2]
2+) readily catalyzes both the polymerization and the hydroamination of styrene. This atypical reactivity underscores the strong σ‐accepting properties of the dicationic antimony ligand and its activating impact on the gold center. Building on these original results, we have chosen to investigate antimonysubstituted 2,2′-bipyridine (bipy) ligands in order to determine if the redox activity of the peripheral antimony center could be used to influence the reactivity of a transition metal coordinated to the bipy ligand. To this end, we synthesized 4-diphenylstibino-2,2′-bipyridine (54), which could be obtained by reaction of 4-lithio-2,2′-bipyridine with Phv2SbCl. The ligand 54 was treated with Pt(CHv3CN)v2Clv2 to afford the platinum complex 55. Interestingly, the latter reacts with PhIClv2 to afford 56, a complex in which the peripheral stibine moiety has been converted into a dichlorostiborane. Complexes 55 and 56 have both been fully characterized. Computational, UV–vis, and cyclic voltammetry studies show that oxidation of the antimony atom leads to a lowering of the bipy-centered LUMO, indicating that 56 is more electron deficient than 55. A congruent picture emerges from reactivity studies, which show that 56 is a more active catalyst for the hydroarylation of ethyl propiolate by mesitylene.
A similar concept was also applied to cyclometalated iridium(III) complexes. Reaction of 4-(diphenylstibino)-2,2′-bipyridine (54) with [(ppy)v2Ir(-Cl)]v2 afforded the corresponding tris-chelate iridium complex [(ppy)v2Ir(54) ] + ([64] + ) which was isolated as a hexafluorophosphate salt ([64][PF
6]). Reaction of [64][PF
6] with excess PhIClv2 in DMSO induced the conversion of the diphenylantimony moiety of [65] + into an anionic diphenyltrichloroantimonate leading to a zwitterionic complex referred to as 65-Cl. Complexes [64][PF
6] and 65-Cl have been characterized by NMR and the structure of 65- Cl confirmed using X-ray diffraction. DFT…
Advisors/Committee Members: Gabbaï, François P. (advisor), Hall, Michael (committee member), Nippe, Michael (committee member), Wu, Hung-Jen (committee member).
Subjects/Keywords: antimony; organometallic; catalysis; Lewis acid; ligand design; gold; platinum; iridium
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APA (6th Edition):
Lo, Y. H. (2019). Coordination and Redox Chemistry of Antimony-Based Ligands and Applications in Organometallic Catalysis. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/188767
Chicago Manual of Style (16th Edition):
Lo, Ying Hao. “Coordination and Redox Chemistry of Antimony-Based Ligands and Applications in Organometallic Catalysis.” 2019. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/188767.
MLA Handbook (7th Edition):
Lo, Ying Hao. “Coordination and Redox Chemistry of Antimony-Based Ligands and Applications in Organometallic Catalysis.” 2019. Web. 01 Mar 2021.
Vancouver:
Lo YH. Coordination and Redox Chemistry of Antimony-Based Ligands and Applications in Organometallic Catalysis. [Internet] [Doctoral dissertation]. Texas A&M University; 2019. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/188767.
Council of Science Editors:
Lo YH. Coordination and Redox Chemistry of Antimony-Based Ligands and Applications in Organometallic Catalysis. [Doctoral Dissertation]. Texas A&M University; 2019. Available from: http://hdl.handle.net/1969.1/188767
Texas A&M University
6.
Dickie, Courtney Marie.
Magnetic and Spectroscopic Properties of Heterometallic Lanthanide Compounds and Towards Utilizing Synchrotron Mössbauer Spectroscopy for Magnetic Relaxation Measurements.
Degree: PhD, Chemistry, 2018, Texas A&M University
URL: http://hdl.handle.net/1969.1/188933
► Single-molecule magnets (SMMs) have attracted considerable attention for their fascinating properties and exciting potential applications in next generation high-density data storage and quantum computing. SMMs…
(more)
▼ Single-molecule magnets (SMMs) have attracted considerable attention for their fascinating
properties and exciting potential applications in next generation high-density data storage and
quantum computing. SMMs are a class of paramagnetic compounds defined by a bistable magnetic
ground state and an energy barrier (U) to reorientation of their molecular spin. Towards the utilization
of SMMs in devices, the development of methods for the control of magnetic properties via
external stimuli is required. A major objective of this research project has been the development
of lanthanide-based SMMs featuring a redox-active transition metal center, with the ultimate goal
of utilizing the redox properties of the transition metal to modulate the magnetization dynamics at
the nearby lanthanide center.
Early results in developing mixed d-block/f-block systems led to the isolation of the
dysprosium-isocarbonyl compound, [(thf)v5Dy((u-OC)W(CO)v2Cp)v3]·thf. Notably, this was the
the first structurally characterized dysprosium-isocarbonyl compound. The static and dynamic
magnetic properties of [(thf)v5Dy((µ-OC)W(CO)v2Cp)v3]·thf were characterized, revealing field-induced slow relaxation only in a magnetically dilute sample (12:1 Y
3+:Dy
3+) with Uveff = 12.6
cm
-1. However, due to instability towards oxidation/reduction, these isocarbonyl compounds were
determined to be unsuitable for redox-switchability applications. A possible route to improved
magnetization dynamics is through the development of low-coordinate lanthanide-isocarbonyl
compounds. Towards this goal, the new, bulky tungsten hydride compound, HWCp
BIG(CO)v3
(HCp
BIG = HCv5(4-n-Bu-Cv6Hv4)v5) was isolated. Gratifyingly, HWCp
BIG(CO)v3 is soluble in
non-coordinating solvents, including hexanes and toluene.
The highly reversible redox properties of ferrocence, FeCpv2, make it ideal for use
in redox-switchability applications. Towards this goal, dysprosium(III) and erbium(III)
bis(diamidoferrocene) complexes have been developed and their dynamic magnetic properties
investigated. The Dy
3+ compound exhibits either "on/off" or "slow/fast" switching in the presence
or absence of a dc field, respectively. The Er
3+ compound exhibits "on/off" functionality in the presence of a dc field. UV-vvis-NIR spectroscopy,
57Fe Mössbauer spectroscopy, and electrochemical studies support the presence of electronic communication between the mixed-valent Fe ions in both solution and in the solid state. This molecular level study is intended to provide the foundation for future switchable solid materials based on the redox properties of ferrocene/ferrocenium.
The cyclopentadienide (Cp
-) substitution chemistry of chromocene was investigated as a synthetic
route for the generation of transition metal precursors for d-block/f-block complexes. The reaction
between chromocene and two equivalents of K(N(SiMve3)v2) generated the polymeric species,
[(N(SiMev3)v2)v2K]v∞ Carrying out the reaction in the presence of cryptand-222 afforded the
mononuclear compound [K(crypt-222)][CpCr(N(SiMev3)v2)v2].…
Advisors/Committee Members: Nippe, Michael (advisor), Gabbai, François P (committee member), Hughbanks, Timothy (committee member), Abanov, Artem G (committee member).
Subjects/Keywords: molecular magnetism; lanthanide chemistry; coordination chemistry; synchrotron Mössbauer spectroscopy; spectroscopy
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APA ·
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APA (6th Edition):
Dickie, C. M. (2018). Magnetic and Spectroscopic Properties of Heterometallic Lanthanide Compounds and Towards Utilizing Synchrotron Mössbauer Spectroscopy for Magnetic Relaxation Measurements. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/188933
Chicago Manual of Style (16th Edition):
Dickie, Courtney Marie. “Magnetic and Spectroscopic Properties of Heterometallic Lanthanide Compounds and Towards Utilizing Synchrotron Mössbauer Spectroscopy for Magnetic Relaxation Measurements.” 2018. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/188933.
MLA Handbook (7th Edition):
Dickie, Courtney Marie. “Magnetic and Spectroscopic Properties of Heterometallic Lanthanide Compounds and Towards Utilizing Synchrotron Mössbauer Spectroscopy for Magnetic Relaxation Measurements.” 2018. Web. 01 Mar 2021.
Vancouver:
Dickie CM. Magnetic and Spectroscopic Properties of Heterometallic Lanthanide Compounds and Towards Utilizing Synchrotron Mössbauer Spectroscopy for Magnetic Relaxation Measurements. [Internet] [Doctoral dissertation]. Texas A&M University; 2018. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/188933.
Council of Science Editors:
Dickie CM. Magnetic and Spectroscopic Properties of Heterometallic Lanthanide Compounds and Towards Utilizing Synchrotron Mössbauer Spectroscopy for Magnetic Relaxation Measurements. [Doctoral Dissertation]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/188933
Texas A&M University
7.
Yang, Mengxi.
Neutral and Cationic Organoantimony Compounds as Lewis Acid Catalysts.
Degree: PhD, Chemistry, 2018, Texas A&M University
URL: http://hdl.handle.net/1969.1/192057
► Organoantimony(V) compounds are potent Lewis acids which have been used for the complexation of anions or for the catalysis of organic reactions. Inspired by the…
(more)
▼ Organoantimony(V) compounds are potent Lewis acids which have been used for the complexation of anions or for the catalysis of organic reactions. Inspired by the broad range of applications developed for the stable Group 13 Lewis acid B(Cv6Fv5)v3, as well as the fact that SbFv5 is more acidic than BFv3, we set out to investigate organoantimony compounds in the context of Lewis acid catalysis. To this end, we synthesized electrophilic Sb(III) and Sb(V) complexes featuring electron-withdrawing halogenated ligands, cationic charges, and/or ancillary donor ligands, and tested these compounds in a number of organic transformations. Computational studies of their electronic structures provided us with insights into their unusual properties.
We compared a series of triarylstibines with their tetrachlorocatecholate stiborane analogs, and demonstrated that the Lewis acidity of organoantimony(III) species can be readily enhanced by oxidation to the +V state, a phenomenon that is rationalized by the lowering of the antimony-based accepting Ó* orbital and a “deepening” of the associated Ó-hole upon oxidation. We also reported the synthesis of triarylfluoro- and triarylchloro- stibonium cations, among which the trimesitylchlorostibonium hexachloroantimonate is free from direct cation-anion interactions due to the steric shielding provided by the mesityl substituents. However, this cation is not as reactive as its phenyl derivative in the catalytic polymerization of THF and the Friedel-Craft dimerization of 1,1-diphenlyethylene. Additionally, we evaluated a series of tetraarylstibonium cations as catalysts for the cycloaddition of isocyanates to oxiranes. While all stibonium cations
favor the 3,4-oxazolidinone products, the bulkier cations are found to be the most selective. Furthermore, we compared a series of ortho-phenylene based pnictogen cations and dications with their monofunctional derivatives as catalysts for the transfer hydrogenation of quinone derivatives with Hantzsch ester, and found that their catalytic reactivity follows the Lewis acidity trend in the order Sb dication > Sb monocation > P monocation. Lastly, this dissertation also investigates the electronic structures of selected organoantimony(V) compounds with the view to understand how coordination events at the antimony center affect the photophysical properties of these compounds.
Advisors/Committee Members: Gabbai, Francois P (advisor), Hall, Michael B (committee member), Nippe, Michael (committee member), Lutkenhaus, Jodie L (committee member).
Subjects/Keywords: antimony; Lewis acids; catalysis; molecular recognition; main-group
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APA (6th Edition):
Yang, M. (2018). Neutral and Cationic Organoantimony Compounds as Lewis Acid Catalysts. (Doctoral Dissertation). Texas A&M University. Retrieved from http://hdl.handle.net/1969.1/192057
Chicago Manual of Style (16th Edition):
Yang, Mengxi. “Neutral and Cationic Organoantimony Compounds as Lewis Acid Catalysts.” 2018. Doctoral Dissertation, Texas A&M University. Accessed March 01, 2021.
http://hdl.handle.net/1969.1/192057.
MLA Handbook (7th Edition):
Yang, Mengxi. “Neutral and Cationic Organoantimony Compounds as Lewis Acid Catalysts.” 2018. Web. 01 Mar 2021.
Vancouver:
Yang M. Neutral and Cationic Organoantimony Compounds as Lewis Acid Catalysts. [Internet] [Doctoral dissertation]. Texas A&M University; 2018. [cited 2021 Mar 01].
Available from: http://hdl.handle.net/1969.1/192057.
Council of Science Editors:
Yang M. Neutral and Cationic Organoantimony Compounds as Lewis Acid Catalysts. [Doctoral Dissertation]. Texas A&M University; 2018. Available from: http://hdl.handle.net/1969.1/192057
. 
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