Di- and Trinuclear Mixed-Valence Copper Amidinate Complexes from Reduction of Iodine

Molecular examples of mixed-valence copper complexes through chemical oxidation are rare but invoked in the mechanism of substrate activation, especially oxygen, in copper-containing enzymes. To examine the cooperative chemistry between two metals in close proximity to each other we began studying the reactivity of a dinuclear Cu(I) amidinate complex. The reaction of [(2,6-Me2C6H3N)2C(H)]2Cu2, 1, with I2 in tetrahydrofuran (THF), CH3CN, and toluene affords three new mixed-valence copper complexes [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I3)(THF)2, 2, [(2,6-Me2C6H3N)2C(H)]2Cu2(μ2-I) (NCMe)2, 3, and [(2,6-Me2C6H3N)2C(H)]3Cu3(μ3-I)2, 4, respectively. The first two compounds were characterized by UV-vis and electron paramagnetic resonance spectroscopies, and their molecular structure was determined by X-ray crystallography. Both di- and trinuclear mixed-valence intermediates were characterized for the reaction of compound 1 to compound 4, and the molecular structure of 4 was determined by X-ray crystallography. The electronic structure of each of these complexes was also investigated using density functional theory

Structure and properties of [(4,6-tBu2C6H2O)2Se]2An(THF)2, An = U, Np, and their reaction with p-benzoquinone.

The synthesis and characterization of U(iv) and Np(iv) selenium bis(phenolate) complexes are reported. The reaction of two equivalents of the U(iv) complex with p-benzoquinone results in the formation of a U(v)-U(v) species with a bridging reduced quinone. This represents a rare example of high-valent uranium chemistry as well as a rare example of a neptunium aryloxide complex

Structure of Uranium(V) Methyl and Uranium(IV) Ylide Complexes

Syntheses of rare examples of U(V) methyl and U(IV) ylide complexes are reported. Reaction of the previously reported U(IV) imido complex [(C 5Me 5) 2U(py)(═NMes)] (py = pyridine, and Mes = 2,4,6-Me 3C 6H 2) with CuI forms the U(V) complex [(C 5Me 5) 2U(I)(═NMes)]. Reaction of the iodo complex with MgMe 2 produces the methyl complex [(C 5Me 5) 2U(CH 3)(═NMes)]. The methyl complex was reacted with CH 2PPh 3, surprisingly forming [(C 5Me 5) 2U(CH 2PPh 3)(═NMes)], a U(IV) ylide. This is formed from a disproportionation of a transient U(V) carbene, leading to the U(IV) ylide and a U(VI) bis(imido) complex, [(C 5Me 5) 2U(═NMes) 2]. These complexes were characterized using spectroscopic methods (nuclear magnetic resonance, infrared, and ultraviolet-visible-nean infrared), SQUID magnetometry, and X-ray crystallography, and density functional theory calculations are used to compare the U(V) methyl with the targeted U(V) carbene ligands

Site-Specific Metal Chelation Facilitates the Unveiling of Hidden Coordination Sites in an Fe II/Fe III -Seamed Pyrogallol[4]arene Nanocapsule

Under suitable conditions, C-alkylpyrogallol­[4]­arenes (PgCs) arrange into spherical metal–organic nanocapsules (MONCs) upon coordination to appropriate metal ions. Herein we present the synthesis and structural characterization of a novel FeII/FeIII-seamed MONC, as well as studies related to its electrochemical and magnetic behaviors. Unlike other MONCs that are assembled through 24 metal ions, this nanocapsule comprises 32 Fe ions, uncovering 8 additional coordination sites situated between the constituent PgC subunits. The FeII ions are likely formed by the reducing ability of DMF used in the synthesis, representing a novel synthetic route toward polynuclear mixed-valence MONCs

Triple Combination Antiviral Drug (TCAD) Composed of Amantadine, Oseltamivir, and Ribavirin Impedes the Selection of Drug-Resistant Influenza A Virus

Widespread resistance among circulating influenza A strains to at least one of the anti-influenza drugs is a major public health concern. A triple combination antiviral drug (TCAD) regimen comprised of amantadine, oseltamivir, and ribavirin has been shown to have synergistic and broad spectrum activity against influenza A strains, including drug resistant strains. Here, we used mathematical modeling along with three different experimental approaches to understand the effects of single agents, double combinations, and the TCAD regimen on resistance in influenza in vitro, including: 1) serial passage at constant drug concentrations, 2) serial passage at escalating drug concentrations, and 3) evaluation of the contribution of each component of the TCAD regimen to the suppression of resistance. Consistent with the modeling which demonstrated that three drugs were required to suppress the emergence of resistance in influenza A, treatment with the TCAD regimen resulted in the sustained suppression of drug resistant viruses, whereas treatment with amantadine alone or the amantadine-oseltamivir double combination led to the rapid selection of resistant variants which comprised ∼100% of the population. Furthermore, the TCAD regimen imposed a high genetic barrier to resistance, requiring multiple mutations in order to escape the effects of all the drugs in the regimen. Finally, we demonstrate that each drug in the TCAD regimen made a significant contribution to the suppression of virus breakthrough and resistance at clinically achievable concentrations. Taken together, these data demonstrate that the TCAD regimen was superior to double combinations and single agents at suppressing resistance, and that three drugs at a minimum were required to impede the selection of drug resistant variants in influenza A virus. The use of mathematical modeling with multiple experimental designs and molecular readouts to evaluate and optimize combination drug regimens for the suppression of resistance may be broadly applicable to other infectious diseases

Post Flow-Through Experiment Characterization of Volcanic Tuff and Carbonate Rock Cores from the Nevada Test Site

(Statement of Responsibility) by Justin R. Walensky(Thesis) Thesis (B.A.) -- New College of Florida, 2005(Electronic Access) RESTRICTED TO NCF STUDENTS, STAFF, FACULTY, AND ON-CAMPUS USE(Bibliography) Includes bibliographical references.(Source of Description) This bibliographic record is available under the Creative Commons CC0 public domain dedication. The New College of Florida, as creator of this bibliographic record, has waived all rights to it worldwide under copyright law, including all related and neighboring rights, to the extent allowed by law.(Local) Faculty Sponsor: Sherman, Suzann

Phosphorano-Stabilized Carbene Complexes with Short Thorium(IV)– and Uranium(IV)–Carbon Bonds

While no alkylidene complexes of the f elements are known, the use of phosphorano-stabilized carbene complexes to produce short actinide–carbon bonds has been previously demonstrated. Complexes of the form, (C₅Me₅)₂­An­(X)­(CHPPh₃), with short thorium­(IV)– and uranium­(IV)–carbon­(carbene) bonds have been synthesized from the reaction of (C₅Me₅)₂­An­(X)­(CH₃) (An = Th, U; X = Cl, Br, or I) with the ylide, CH₂​PPh₃. The resulting uranium complexes feature the shortest uranium­(IV)–carbon bonds reported to date. The molecular and electronic structure of the thorium phosphorano-stabilized carbene complexes is detailed using X-ray crystallography, ¹³C NMR spectroscopy, and density functional theory calculations, and compared to thorium methandiide complexes

Phosphorano-Stabilized Carbene Complexes with Short Thorium(IV)– and Uranium(IV)–Carbon Bonds

While no alkylidene complexes of the f elements are known, the use of phosphorano-stabilized carbene complexes to produce short actinide–carbon bonds has been previously demonstrated. Complexes of the form, (C₅Me₅)₂­An­(X)­(CHPPh₃), with short thorium­(IV)– and uranium­(IV)–carbon­(carbene) bonds have been synthesized from the reaction of (C₅Me₅)₂­An­(X)­(CH₃) (An = Th, U; X = Cl, Br, or I) with the ylide, CH₂​PPh₃. The resulting uranium complexes feature the shortest uranium­(IV)–carbon bonds reported to date. The molecular and electronic structure of the thorium phosphorano-stabilized carbene complexes is detailed using X-ray crystallography, ¹³C NMR spectroscopy, and density functional theory calculations, and compared to thorium methandiide complexes

Phosphorano-Stabilized Carbene Complexes with Short Thorium(IV)– and Uranium(IV)–Carbon Bonds

While no alkylidene complexes of the f elements are known, the use of phosphorano-stabilized carbene complexes to produce short actinide–carbon bonds has been previously demonstrated. Complexes of the form, (C₅Me₅)₂­An­(X)­(CHPPh₃), with short thorium­(IV)– and uranium­(IV)–carbon­(carbene) bonds have been synthesized from the reaction of (C₅Me₅)₂­An­(X)­(CH₃) (An = Th, U; X = Cl, Br, or I) with the ylide, CH₂​PPh₃. The resulting uranium complexes feature the shortest uranium­(IV)–carbon bonds reported to date. The molecular and electronic structure of the thorium phosphorano-stabilized carbene complexes is detailed using X-ray crystallography, ¹³C NMR spectroscopy, and density functional theory calculations, and compared to thorium methandiide complexes