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High and low valent nickel complexes supported by tridentate and tetradentate ligands relevant for C–C bond formation reactions
Get PDFSubmission published under a 24 month embargo labeled 'Closed Access', the embargo will last until 2023-12-01The student, Leonel Griego, accepted the attached license on 2021-12-01 at 15:00.The student, Leonel Griego, submitted this Dissertation for approval on 2021-12-01 at 15:36.This Dissertation was approved for publication on 2021-12-03 at 09:01.DSpace SAF Submission Ingestion Package generated from Vireo submission #17296 on 2022-04-29 at 16:10:10Made available in DSpace on 2022-04-29T21:58:34Z (GMT). No. of bitstreams: 3
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Reason: Author requested closed access (OA after 2yrs) in Vireo ETD systemAuthor requested closed access (OA after 2yrs) in Vireo ETD systemLimitedNickel (Ni) complexes stabilized by multidentate ligands are known to be efficient catalysts for a wide range of cross-coupling reactions, including those involving Csp3–Csp3 coupling. Although many Ni0/NiII systems have been reported as potential species in catalysis, newer studies suggest that their odd-electron NiI/NiIII counterparts are also viable catalytic intermediates. Our goal is to isolate these rare oxidation states especially those containing organometallic intermediates. Herein, we discuss the isolation of key Ni intermediates in the +1, +2, and +3 oxidation states supported by various N-based macrocycles.
In this work, we provide direct evidence for a NiI/NiII/NiIII catalytic cycle by using a bulky 1,4,7-triisopropyl-1,4,7-triazacyclononane ligand (iPr3TACN). The oxidation of the corresponding NiII-dimethyl complex with weak oxidants yields a paramagnetic NiIII-dimethyl complex that was characterized by EPR. In addition, reductive elimination of ethane in quantitative yields was detected by NMR, while a direct formation of NiI species was observed by carefully monitoring the 2e- transformation by EPR. In addition, various NiI species were characterized via EPR and reactivity tested. The combined results further confirmed that the bulky iPr3TACN ligand framework can stabilize Ni in several oxidation states that are relevant for cross-coupling catalysis.
Furthermore, two new classes of macrocyclic ligands and their ability to stabilized high- valent Ni centers have been studied. The first class includes chiral macrocyclic ligands that have been successfully synthesized and characterized. The R*N3CBr and R*N4 (R* = phenethyl, PE or methylneopentyl, MeNp) pyridinophanes allowed for the isolation of various Ni complexes including the rare high-valent [(PEN3C)NiIII(MeCN)2](PF6)2 complex. The reactivity of the chiral Ni complexes has been tested demonstrating slight enantioselectivity induced by the chiral ligands.
In addition, a second class of cross-bridged cyclam/cyclen macrocyclic ligands was studied as their Ni(II)Cl2 complexes demonstrated accessible high-valent Ni(III) species.
To conclude, preliminary results have shown the (iPr3TACN)Ni complexes are efficient catalysts in the Kumada coupling reactions of alkyl electrophiles with alkyl Grignards, raising the possibility of exploring other types of cross-coupling reactions. In addition, the iPr3TACN ligand framework has allowed for the isolation of a novel [(iPr3TACN)NiIIMe]PF6, a Ni-monomethyl complex that has been elusive with RN4 (R = Me, iPr, tBu) and MeTACN ligand systems. The isolation of this complex opens the possibility of exploring a more bioinorganic side of the iPr3TACN, as Ni–Me complexes are proposed as key intermediates CODH/acetyl coenzyme A synthase (ACS) and methyl coenzyme M reductase (MCR) systems
Going Beyond Counting First Authors in Author Co-citation Analysis
Get PDFThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Variations on the Author
Get PDF“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Get PDFWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
Dispelling the Myths Behind First-author Citation Counts
Get PDFWe conducted a full-scale evaluative citation analysis study of scholars in the XML research field to explore just how different from each other author rankings resulting from different citation counting methods actually are, and to demonstrate the capability of emerging data and tools on the Web in supporting more realistic citation counting methods. Our results contest some common arguments for the continued
use of first-author citation counts in the evaluation of scholars, such as high correlations between author rankings by first-author citation counts and other citation
counting methods, and high costs of using more realistic citation counting methods that are not well-supported by the ISI databases. It is argued that increasingly available digital full text research papers make it possible for citation analysis studies to go beyond what the ISI databases have directly supported and to employ more
sophisticated methods
koamabayili/VECTRON-author-checklist: VECTRON author checklist
No full textWe have done our best to complete the author checklist relating to the use of animals in the hut study. Note that the objective for the hut study was to evaluate the IRS treatment applications for residual efficacy against Anopheles mosquitoes, including the local An. coluzzii mosquito population. Cows were only used to attract mosquitoes into the huts and no tests were carried out directly on the cows. The author checklist is intended for use with studies where experiments are carried out on animals, which is why we have had such difficulty in completing this for the hut study, as many of the questions do not relate to how the cows were used
Author-wise bibliometric analysis based on entropy.
No full textAuthor-wise bibliometric analysis based on entropy.</p
Author Under Sail The Imagination of Jack London, 1893-1902
No full textIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Intro -- Title Page -- Copyright Page -- Dedication -- Contents -- Acknowledgments -- Introduction -- 1. Spirit Truth -- 2. From Absorption to Theatricality and Back Again -- 3. "I Will Build a New Present" -- 4. Sons as Authors -- 5. Fathers as Publishers -- 6. The Daughter as Author -- 7. Lovers as Authors -- 8. At Sea with the Family -- 9. Yellow News, Yellow Stories -- 10. The Return Home -- Notes -- Bibliography -- Index -- About Jay WilliamsIn Author Under Sail, Jay Williams offers the first complete literary biography of Jack London as a professional writer engaged in the labor of writing. It examines the authorial imagination in London's work, the use of imagination in both his fiction and nonfiction, and the ways he defined imagination in the creative process in his business dealings with his publishers, editors, and agents. In this first volume of a two-volume biography, Williams traverses the years 1893 to 1902, from London's "Story of a Typhoon" to The People of the Abyss. The Jack London who emerges in the pages of Author Under Sail is a writer whose partnership with publishers, most notably his productive alliance with George Brett of Macmillan, was one of the most formative in American literary history. London pioneered many author models during the heyday of realism and naturalism, blurring the boundaries of these popular genres by focusing on absorption and theatricality and the representation of the seen and unseen. London created an impassioned, sincere, and extremely personal realism unlike that of other American writers of the time. Author Under Sail is a literary tour de force that reveals the full range of London as writer, creative citizen, and entrepreneur at the same time it sheds light on the maverick side of machine-age literature.Description based on publisher supplied metadata and other sources.Electronic reproduction. Ann Arbor, Michigan : ProQuest Ebook Central, YYYY. Available via World Wide Web. Access may be limited to ProQuest Ebook Central affiliated libraries
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