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161 Glass: Site Specific Music in an Artistic Context

Description: The composition 161 Glass is a 17-minute musical work with percussion, wind and brass instruments in which the intersection of mid-century architecture, and the art and culture of a dynamic city are inextricably linked. Through this paper, I explore the process of composing a musical work in relationship to the significance of site specific context. The paper begins by defining the concept of site specific art works; then reviews the discourse of the intersection of art, music and architecture. I then delve into the cultural and geographic context surrounding this project from the modern era through the present, and how those perspectives apply to the building and my piece. I reveal how the composition relates the musical ideas to the site. Finally, I describe the collaborative process between myself, the musicians and the Dallas Contemporary staff.
Date: May 2010
Creator: Rusnak, Christina S.

Adaptive Advantages of Carotenoid Pigments in Alpine and Subalpine Copepod Responses to Polycyclic Aromatic Hydrocarbon Induced Phototoxicity

Description: Alpine zooplankton are exposed to a variety of stressors in their natural environment including ultraviolet radiation. Physiological coping mechanisms such as the accumulation of photoprotective compounds provide these zooplankton protection from many of these stressors. Elevated levels of carotenoid compounds such as astaxanthin have been shown to help zooplankton survive longer when exposed to ultraviolet radiation presumably due to the strong antioxidant properties of carotenoid compounds. This antioxidant capacity is important because it may ameliorate natural and anthropogenic stressor-induced oxidative stress. While previous researchers have shown carotenoid compounds impart increased resistance to ultraviolet radiation in populations of zooplankton, little work has focused on the toxicological implications of PAH induced phototoxicity on zooplankton containing high levels of carotenoid compounds. This thesis discusses research studying the role that carotenoid compounds play in reducing PAH induced phototoxicity. By sampling different lakes at elevations ranging from 9,500' to 12,700' in the front range of the Colorado Rocky Mountains, copepod populations containing different levels of carotenoid compounds were obtained. These populations were then challenged with fluoranthene and ultraviolet radiation. Results discussed include differences in survival and levels of lipid peroxidation among populations exhibiting different levels of carotenoid compounds, and the toxicological and ecological implications of these results.
Date: May 2010
Creator: Kovach, Matthew James

"Among Waitresses": Stories and Essays

Description: The following collection represents the critical and creative work produced during my doctoral program in English. The dissertation consists of Part I, a critical preface, and Part II, a collection of seven short stories and two nonfiction essays. Part I, which contains the critical preface entitled "What to Say and How to Say It," examines the role of voice in discussions of contemporary literature. The critical preface presents a definition of voice and identifies examples of voice-driven writing in contemporary literature, particularly from the work of Mary Robison, Dorothy Allison, and Kathy Acker. In addition, the critical preface also discusses how the use of flavor, tone, and content contribute to voice, both in work of famous authors and in my own writing. In Part II of my dissertation, I present the creative portion of my work. Part II contains seven works of short fiction, titled "Among Waitresses," "The Lion Tamer," "Restoration Services," "Hospitality," "Blood Relation," "Managerial Timber," and "Velma A Cappella." Each work develops a voice-driven narrative through the use of flavor, tone, and content. Also, two nonfiction essays, titled "Fentanyl and Happy Meals" and "Tracks," close out the collection. "Fentanyl and Happy Meals" describes the impact of methamphetamine addiction on family relationships, while "Tracks" focuses on the degradation of the natural world by human waste and other forms of pollution. In total, this collection demonstrates my approach to both scholarly and creative writing, and I am grateful for the University of North Texas for the opportunity to develop academically and achieve my goals.
Date: May 2010
Creator: Hobbs, Jessica

Analysis of Graduation Rates for Four-year Colleges: A Model of Institutional Performance Using IPEDS

Description: Under the George W. Bush U.S. presidential administration, the federal government pushed for greater accountability among institutions of higher education for educational outcomes. Graduation rate is a key performance indicator of institutional accountability. Previous researchers of student attrition focused primarily on the effects of student level factors on student persistence/withdrawal behavior. Recently, researchers put more focus on the effects of institutional characteristics on graduation rates, but most of these studies were exploratory and based on multiple regression models. No institutional model has existed to synthesize their results within a theoretical framework. Such an institutional model is needed to explain the process of student persistence at the institutional level. The purpose of this study was to develop a model of institutional performance in graduation rate for four-year, public and private not-for-profit, Title IV institutions in the United States. This study validated the institutional model based on the IPEDS dataset using the structural equation modeling (SEM) technique. Further group comparison analyses are conducted by fitting the same SEM model to several subgroup datasets based on grouping variables such as control, geographical region and state. Benchmarking analyses were conducted to demonstrate how administrators and policy-makers can use the institutional model to compare the performance of an institution with its peers and what policy changes can they pursue to improve graduation rates.
Date: May 2010
Creator: Fung, Terence Yip-hung

An Analysis of Interrater Agreement Between the Motivation Assessment Scale (MAS), Questions About Behavioral Function (QABF), and Analog Assessment Outcomes

Description: An analysis of interrater agreement across multiple respondents on anecdotal assessments was compared with experimental functional analysis outcomes for correspondence. Experiment 1 evaluated the agreement of multiple respondents on the function of problem behavior for 22 individuals across 42 target behaviors using the Motivation Assessment Scale (MAS) and the Questions About Behavioral Function (QABF). Results showed agreement on the primary maintaining consequence for 4 or 5 of the 5 respondents in 52% (22/42) of the individual's target behaviors with the MAS and 57% (24/42) with the QABF. Experiment 2 examined whether correspondence occurred between the anecdotal assessment results and experimental functional analysis (EFA) results for 7 individuals selected from Experiment 1. Correspondence between the QABF assessment and the EFA was found for 6 of 7 participants, and 4 of the 7 showed correspondence between the EFA and the MAS. This study showed that the QABF had higher correspondence with analog assessments than the MAS thus, supporting the previous findings of Paclawskyj et al. (2001).
Date: May 2010
Creator: Smith, Carla Michelle

An Analysis of Performance Differences Between Self-Directed and Teacher-Directed Alternative Education Campuses in Texas

Description: This study was conducted to analyze the performance differences between alternative education campuses in Texas that used teacher-directed strategies and those that used self-directed strategies. The study was also conducted to inform educators of the results these two strategies had achieved with at-risk students during the three years of 2006-2008. The study used the results from the Texas Assessment of Knowledge and Skills test as reported in the AEIS annual reports from the Texas Education Agency. Alternative education schools were grouped according to the strategy used to educate at-risk students. The results of the statistical tests showed the two strategies had similar performance results and there was no statistical difference between the two. The results offered several implications concerning the ability of at-risk students to achieve in alternative education schools including possible reasons why students who were previously unsuccessful became successful in alternative settings. The report also addressed the number of students who continued to be unsuccessful even when placed on an alternative education campus. Possible reasons for this continued inability to succeed are discussed. Recommendations for further research were listed at the conclusion of the study.
Date: May 2010
Creator: Wimberley, Alan

An Analysis of UNT Commuting Patterns

Description: Academic institutions have recently organized to address their campus' greenhouse gas emissions. Along those lines, the University of North Texas (UNT) pledged to minimize the campus' environmental impact, and conducted a transportation survey in May 2009. The analyses confirm that commuting to campus was the second highest source (29%) of UNT's greenhouse gas emissions, following purchased electricity (48%). Students, faculty and staff drive over 89 million miles per year, 84% of which comes from students. Forty‐two percent of student driving trips originate in the primary and secondary core areas surrounding Denton, which are partially served by buses. However, because these core areas are in close proximity to the campus, they contribute only 8% of the total student driving distance. Beyond the Denton core, the inner periphery of Denton County contributes another 22% of driving mileage. Students living in the outer periphery (outside Denton County) contribute the remaining 70% of total driving distance, and carpooling is currently their only alternative.
Date: May 2010
Creator: Waskey, Susan L.

An Annotated Bibliography of Selected Music for Saxophone by Charles Ruggiero with an Analysis of Interplay for Soprano Saxophone and Piano

Description: Ruggiero's contributions to contemporary music are noteworthy. They include 27 works written for solo instruments, voice, as well as chamber groups and large ensembles. This study serves as an annotated bibliography of selected works written for saxophone by Charles Ruggiero. They include a piece for large chamber ensemble, Dig: From Tunes My Grandmother Heard (2009), a trio for flute, clarinet, and alto saxophone titled Echoes of "Piano Red" (2006), two saxophone quartets, Dig: JSB 1 (2003), and Three Blues for Saxophone Quartet (1981), two works for alto saxophone and piano, Night Songs and Flights of Fancy (2005), and Strayhorn (1999-2000), one piece for soprano saxophone and piano, Interplay for Soprano Saxophone and Piano (1988), a single movement work for alto saxophone, piano, winds, and percussion, Dance Complusions (2004), one duo for tenor saxophone and percussion, Sizzlesax II (2001), one concerto for soprano saxophone and piano, Concerto for Soprano Saxophone and Orchestra (1995, rev. 1999), and a trio for violin, alto saxophone, and piano, Dances and Other Movements (1983, rev. 1984). In addition, an analysis of Ruggiero's composition Interplay for Soprano Saxophone and Piano offers an insight into the compositional style of the composer.
Date: May 2010
Creator: Bradfield, Ann

Archaeological Proteomics: Method Development and Analysis of Protein-Ceramic Binding

Description: The analysis of protein residues recovered from archaeological artifacts provides a unique opportunity to reveal new information about past societies. However, many scientists are currently unwilling to accept protein-based results due to problems in method development and a basic lack of agreement regarding the ability of proteins to bind to, and preserve within, artifacts such as pottery. In this paper, I address these challenges by conducting a two-phase experiment. First, I quantitatively evaluate the tendency of proteins to sorb to ceramic matrices by using total organic carbon analysis and spectrophotometric assays to analyze samples of experimentally cooked ceramic. I then test a series of solvent and physical parameters in order to develop an optimized method for extracting and preparing protein residues for identification via mass spectrometry. Results demonstrate that protein strongly sorbs to ceramic and is not easily removed, despite repeated washing, unless an appropriate extraction strategy is used. This has implications for the future of paleodietary, conservation ecology and forensic research in that it suggests the potential for recovery of aged or even ancient proteins from ceramic matrices.
Date: May 2010
Creator: Barker, Andrew L.

An Assessment of Consumers' Willingness to Patronize Foreign-Based Business Format Franchises: An Investigation in the Fast-Food Sector

Description: This study aimed to address consumers' stereotypical categorizations in the form of essentialist views about foreign cultures and their effect on individual consumers, including their negative or aroused emotions and subsequent retail patronage behaviors. The research mission was to empirically assess the salient dimensions of consumers' states of mind (positive and negative affect, psychological essentialism, epistemic curiosity), states of being (store atmospherics), and states of action (retail patronage behaviors) in a cultural context based on Mehrabian-Russell theory of environmental psychology. Specifically, the retail patronage setting was selected as foreign-based fast-food franchises because it represents both a relevant and timely situational context for consumer behavior. This dissertation makes several contributions to international retail patronage literature. First, it frames curiosity as an aroused emotional state and finds support for the relationship between consumer epistemic curiosity and retail patronage. Second, it provides support for the linkage between consumer affect and retail patronage in an international retail setting. Third, it reveals that affect has a greater impact on retail patronage than epistemic curiosity. The overarching finding of this study is an inability to tie the cultural elements in retail atmospherics, including signs, symbols, and artifacts, to consumer emotions. In addition, we were unable to frame psychological essentialism as a personality trait that would reduce the levels of affect and curiosity in retail store environments characterized by foreign-cultural elements.
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Date: May 2010
Creator: Ertekin, Selcuk

An Assessment of Undergraduate Course Syllabi in the Departments of English at Universities in Taiwan

Description: This exploratory, qualitative research explored the extent that course syllabi in the Departments of English in 13 public and 9 private universities in Taiwan reflect the inclusion of syllabus components to promote learning as recommended in the literature in the United States. Research questions included: what components can be inferred from the literature in the U.S. for the recommended components of a course syllabus, for the components for a learning-centered syllabus, and for a model to analyze Bloom's cognitive level of learning? And when these are applied to analyze course syllabi in English courses, are syllabi in these universities congruent with the models? The research identified and analyzed 235 course syllabi from the core courses listed online at these universities. The findings indicated that these syllabi are highly congruent with the syllabus components template; 68% of the syllabi included seven or more of the ten components. Additionally, these syllabi reflect medium congruency with the learning-centered syllabus template. Verbs used in objectives and learning outcomes in different English courses indicate different levels of cognitive learning goals as identified by Bloom's cognitive domain. Additional findings indicate that there was no difference in inclusion of components based on where faculty earned their doctoral degree. This research assumed similarities between higher education in Taiwan and the U.S., conclusions indicate that the course syllabi in Departments of English in Taiwan are congruent with the models recommended in the literature in the U.S.
Date: May 2010
Creator: Lin, Baysan

"Being" a Stickist: A Phenomenological Consideration of "Dwelling" in a Virtual Music Scene

Description: Musical instruments are not static, unchanging objects. They are, instead, things that materially evolve in symmetry with human practices. Alterations to an instrument's design often attend to its ergonomic or expressive capacity, but sometimes an innovator causes an entirely new instrument to arise. One such instrument is the Chapman Stick. This instrument's history is closely intertwined with global currents that have evolved into virtual, online scenes. Virtuality obfuscates embodiment, but the Stick's world, like any instrument's, is optimally related in intercorporeal exchanges. Stickists circumvent real and virtual obstacles to engage the Stick world. Using an organology informed by the work of Heidegger and Merleau-Ponty, this study examines how the Chapman Stick, as a material "thing," speaks in and through a virtual, representational environment.
Date: May 2010
Creator: Hodges, Jeff

Breaking Accidental Behavior Chains.

Description: Accidental behavior chains are a common problem in dog training. Many handlers inadvertently reinforce undesirable behaviors. The behavior analytic literature already contains articles describing methods of breaking chains; however, those methods either are not used in dog training for practical purposes or are ineffective in dog training. This experiment investigated two ways to break a behavior chain, including extending the chain and introducing a delay into the chain. The results of extending the chain showed that it is possible to decrease the target behavior using this method, but it was not eliminated in this study. Adding a delay into the behavior chain resulted in a quick elimination of the target behavior.
Date: May 2010
Creator: McKnight, Debra Gayle

Can These Bones Live? A Collection of Stories

Description: The collection concerns itself with race, gender, masculinity, marginalization, the act of violence as a means of self expression, identity and the performance of identity, love, and loss. The collection also uses historical events-more specifically, events that are central to black culture in Northeast, Ohio- to situate the characters and witness their response to these historical events. I strive to illustrate blackness as both political and fragmented with the characters in my collection. My characters believe that what they are doing-exacting violence, abusing women, disrespecting each other- is somehow the normative; that somehow what it is that they have learned is how they should perform black identity.
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Date: May 2010
Creator: Hoey, Danny M., Jr.

A Case Study of Undergraduate Course Syllabi in Taiwan

Description: Higher education in Taiwan has been influenced by U.S. and Western practices, and syllabi represent one means to verify this. However, limited research exists in Taiwan on course syllabi and on similarities of syllabi with practices in other countries. In the U.S. as the paradigm shifted from teaching to learning and to the learning-centered context, scholars argued that syllabi should be learning-centered. Given the assumption that higher education in Taiwan is similar to U.S. higher education and the call for a learning-centered context, this qualitative research examined 180 undergraduate syllabi at a public university in Taiwan with a (traditional) syllabus component template and a learning-centered syllabus component template derived from the literature in the U.S. to describe (1) the contents of syllabi, and (2) the extent that syllabi in Taiwan were congruent to U. S. syllabus component templates. Syllabi at this university were highly congruent with the (traditional) syllabus component template and were congruent at the medium level with the learning-centered component template. About 90% of syllabi included 8 of 10 major components. Additional findings included: 70% of faculty were male, and 30% were female; more than 75% of the faculty earned their doctoral degrees from the United States or Europe; gender made no difference on inclusion of major components for both templates; there was no difference in inclusion of components on both templates for faculty who earned their doctoral degrees from the U.S. or Taiwan; a high percentage (80%) of college courses adopted English textbooks published in the U.S.; some differences existed and use of English in the syllabus and on components included in the syllabi. Based on these syllabi, it is evident that syllabi in Taiwan represent course planning and organization congruent to recommended practices in the United States.
Date: May 2010
Creator: Tung, Yao-Tsu

The Characteristics of a Community of Practice in a National Writing Project Invitational Summer Institute

Description: This qualitative naturalistic descriptive case study provides an understanding of the characteristics of a community of practice within a National Writing Project Invitational Summer Institute. This study utilized naturalistic, descriptive case study methodology to answer the research question: What characteristics of a community of practice are revealed by the perceptions and experiences of the fellows of a National Writing Project Invitational Summer Institute? Data were gathered in the form of interviews, focus group, observations, field notes, and participant reflective pieces. Peer debriefing, triangulation, thick rich description, as well as member checking served to establish credibility and trustworthiness in the study. Bracketing, a phenomenological process of reflecting on one's own experiences of the phenomenon under investigation was utilized as well. The findings of this study point to five analytic themes. These themes, ownership and autonomy, asset-based environment, relationships, socially constructed knowledge and practices, and experiential learning, intertwine to illuminate the three essential components which must be present for a community of practice to exist: joint enterprise, mutual engagement, and shared repertoire. Participants' portraits provide a description of their unique experiences as they moved fluidly between the periphery and core of the community of practice.
Date: May 2010
Creator: Pearce, Terisa Ronette

Characterizing Noise and Harmonicity: The Structural Function of Contrasting Sonic Components in Electronic Composition

Description: This dissertation examines the role of noise in shaping the form of several recent musical compositions. This study demonstrates how the contrast of noisy sounds and harmonic sounds can impact the structure of compositions. Depending on context, however, the specific use and function of noise can vary substantially from one work to the next. The first portion of this paper describes methods for quantifying noise content using FFT analysis procedures. A number of tests on instrumental and synthetic sound sources are described in order to demonstrate how the analysis system may react to certain sounds. The second part of this document consists of several analyses of whole musical works. Works for acoustic instruments are examined first, followed by works for electronic media. During these analyses, it becomes clear that while the use of noise in each work is based largely upon context, some common patterns do exist across different works. The final portion of the paper examines an original work which was written with the function of noise specifically in mind. The original work is put through the same analysis procedures as works seen earlier in the paper, and some conclusions are drawn regarding both the possibilities and limitations of noise analysis as a compositional tool.
Date: May 2010
Creator: Dribus, John Alexander

Child-Parent Relationship Therapy (CPRT) with Adoptive Families: Effects on Child Behavior, Parent-Child Relationship Stress, and Parental Empathy

Description: This randomized controlled study is a preliminary investigation on the effects of Child-Parent Relationship Therapy (CPRT) with 61 adoptive parents. The participants in this study identified themselves as the following: 54 European American, 3 Black American, 3 Hispanic/Latino, and 1 individual who chose not to indicate ethnicity. The study included 23 couples and 15 individual mothers. The CPRT is a structured, time limited approach that trains caregivers to be an active participant as a therapeutic change agent in their child's life. Results from a two (group) by two (measures) split plot ANOVA indicated that adoptive parents who participated in 10 weeks of CPRT reported statistically significant decreases in child behavior problems and parent child-relationship stress. Statistically significant increases in parent empathy were also reported by raters blinded to the study. CPRT demonstrated a medium to large treatment effect on reducing children's behavior problems and parent-child relationship stress. In addition, CPRT demonstrated a large treatment effect on increasing parental empathy. The results of the study provide preliminary support for CPRT as a responsive intervention for adoptive parents and their children.
Date: May 2010
Creator: Carnes-Holt, Kara

A Comparative Analysis of the 1915 and 1919 Versions of Symphony No. 5 in E-flat Major, op. 82 by Jean Sibelius

Description: The initial composition of the Fifth Symphony in E-flat Major, Op. 82 was undertaken as a commission to celebrate the composer's fiftieth birthday. Unhappy with the initial efforts, two revisions were then performed; the first was in 1916 and the final revision in 1919. Despite the larger form of the work seeming to have been changed between the 1915 and 1919 versions, the smaller gestures of thematic expression in both versions remained similar. On the surface, it had appeared that the composer had eliminated a movement, changing the 1919 version into a three movement form. This view was not challenged by the composer at the time, and since the earlier versions had either been withdrawn or destroyed, there was no way to compare the original efforts to the final product until recently. In comparing the 1919 version to the original, a definite strong parallel can be seen between the two - despite the changes to form, rearrangement of melodic material, and the seemingly different number of movements. However, the parallel is enough that the 1915 version can be a guide to classifying the 1919 version, an act that has eluded many scholars since the 1920s. Most importantly, comparing the two versions shows that the 1919 version is not a three movement form at all; it is a four movement form that is obscured by the connection of the first and second movements by a thematic bridge that contains elements from both movements, but is not placed within either structure.
Date: May 2010
Creator: Norine, John Richard, Jr.

Comparing Indices of Happiness during Teaching Interactions

Description: The measurement of happiness has received increasing attention in behavior analytic literature. Happiness in individuals with developmental disabilities has been assessed by 1) counting a specific behavior, or 2) sampling constellations of behaviors. The purpose of this study was to examine the two approaches while observing nine child and teacher dyads at an autism treatment center. Results showed that, overall, a constellation of behaviors can yield similar patterns when compared to a specific behavior count. However, the affect of one person did not predict the affect of the other and similar instructional conditions did not predict affect either. The implications of these results and future directions are discussed.
Date: May 2010
Creator: Anderson, Claire Therese

Comparing the Effects of Home Versus Clinic-Based Parent Training for Children with Autism

Description: Research with parents on managing child problem behavior typically measures either child or parent behavior. This study was designed to evaluate the effectiveness of training parents to implement a function-based behavior intervention plan (BIP) in a non-trained natural environment utilizing a Multiple Probe Design across Participants. Participants included four parent-child dyads. Measurement variables included parents' use of effective and ineffective strategies and child problem behavior. Intervention involved training parents to understand and implement the BIP using effective strategies, modeling the effective procedures, and providing feedback following parent implementation of procedures. Results showed that the intervention was very effective in promoting skill generalization of parents and decreasing child problem behavior. The findings have implications for research and clinical practice.
Date: May 2010
Creator: Crone, Regina M.

Comparing the Readability of Text Displays on Paper, E-Book Readers, and Small Screen Devices

Description: Science fiction has long promised the digitalization of books. Characters in films and television routinely check their palm-sized (or smaller) electronic displays for fast-scrolling information. However, this very technology, increasingly prevalent in today's world, has not been embraced universally. While the convenience of pocket-sized information pieces has the techno-savvy entranced, the general public still greets the advent of the e-book with a curious reluctance. This lack of enthusiasm seems strange in the face of the many advantages offered by the new medium - vastly superior storage capacity, searchability, portability, lower cost, and instantaneous access. This dissertation addresses the need for research examining the reading comprehension and the role emotional response plays in the perceived performance on e-document formats as compared to traditional paper format. This study compares the relative reading comprehension on three formats (Kindle, iTouch, and paper) and examines the relationship of subject's emotional response and relative technology exposure as factors that affect how the subject perceives they have performed on those formats. This study demonstrates that, for basic reading comprehension, the medium does not matter. Furthermore, it shows that, the more uncomfortable a person is with technology and expertise in the requested task (in this case, reading), the more they cling to the belief that they will do better on traditional (paper) media - regardless of how well they actually do.
Date: May 2010
Creator: Baker, Rebecca Dawn

Comparison of Heteranthera Dubia (Jacq.) MacM.-associated Macroinvertebrates Between Georgraphical Regions in the United States

Description: Macroinvertebrates associated with the aquatic plant, water stargrass (Heteranthera dubia), were sampled from 12 waterbodies in four regions of the United States from June to August 2005. Taxa richness, evenness, and diversity were lowest in the Lower Midwest (LMW) region, and higher in Northern sites, especially the Upper Midwest (UMW), and Northeast (NE). While relative abundance varied from site to site and region to region, utilization of the plant by functional groups remained fairly constant. Collector-gatherers consistently comprised the largest portion of invertebrates sampled. The shredder/ herbivore functional group comprised an average of 17 % of total groups. Through an exhaustive literature review, it was found that shredder/ herbivores of water stargrass have not been reported in the literature. Because of this, the herbivore group was analyzed separately and consisted of 2,383 specimens representing 23 species. The most common groups were Rhopalosiphum sp., Nectopsyche spp. and chironomids. No differences were found in herbivore diversity or evenness between sampling regions, but species richness was significantly different.
Date: May 2010
Creator: Harms, Nathan Earl

Computational Study of Small Molecule Activation via Low-Coordinate Late First-Row Transition Metal Complexes

Description: Methane and dinitrogen are abundant precursors to numerous valuable chemicals such as methanol and ammonia, respectively. However, given the robustness of these substrates, catalytically circumventing the high temperatures and pressures required for such transformations has been a challenging task for chemists. In this work, computational studies of various transition metal catalysts for methane C-H activation and N2 activation have been carried out. For methane C-H activation, catalysts of the form LnM=E are studied, where Ln is the supporting ligand (dihydrophosphinoethane or β-diketiminate), E the activating ligand (O, NCH3, NCF3) at which C-H activation takes place, and M the late transition metal (Fe,Co,Ni,Cu). A hydrogen atom abstraction (HAA) / radical rebound (RR) mechanism is assumed for methane functionalization (CH4 à CH3EH). Since the best energetics are found for (β-diket)Ni=O and (β-diket)Cu=O catalysts, with or without CF3 substituents around the supporting ligand periphery, complete methane-to-methanol cycles were studied for such systems, for which N2O was used as oxygen atom transfer (OAT) reagent. Both monometallic and bimetallic OAT pathways are addressed. Monometallic Fe-N2 complexes of various supporting ligands (LnFe-N2) are studied at the beginning of the N2 activation chapter, where the effect of ligand on N2 activation in end-on vs. side-on N2 isomers is discussed. For (β-diket)Fe-N2 complexes, the additional influence of diketiminate donor atom (N(H) vs. S) is briefly addressed. The remainder of the chapter expands upon the treatment of β-diketiminate complexes. First, the activation and relative stabilities of side-bound and end-bound N2 isomers in monometallic ((β-diket)M-N2) and bimetallic ((β-diket)M-N2-M(β-diket)) first row transition metal complexes are addressed. Second, the thermodynamics of H/H+/H- addition to (β-diket)Fe-bound N2, followed by subsequent H additions up to release of ammonia, is discussed, for which two mechanisms (distal and alternating) are considered. Finally, the chapter concludes with partial distal and alternating mechanisms for H addition to N2 ...
Date: May 2010
Creator: Pierpont, Aaron