Download or read book Improved Modeling of Transition Metals Applications to Catalysis and Technetium Chemistry written by T. R. Cundari and published by . This book was released on 2004 with total page 13 pages. Available in PDF, EPUB and Kindle. Book excerpt: There is considerable impetus for identification of aqueous OM catalysts as water is the ultimate ''green'' solvent. In collaboration with researchers at Ames Lab, we investigated effective fragment and Monte Carlo techniques for aqueous-phase hydroformylation (HyF). The Rh of the HyF catalyst is weakly aquated, in contrast to the hydride of the Rh-H bond. As the insertion of the olefin C=C into Rh-H determines the linear-to-branched aldehyde ratio, it is reasonable to infer that solvent plays an important role in regiochemistry. Studies on aqueous-phase organometallic catalysis were complemented in studies of the gas-phase reaction. A Rh-carbonyl-phosphine catalyst was investigated. Two of the most important implications of this research include (a) pseudorotation among five-coordinate intermediates is significant in HyF, and (b) CO insertion is the rate-determining step. The latter is in contrast to experimental deductions, highlighting the need for more accurate modeling. To this end, we undertook studies of (a) experimentally relevant PR{sub 3} co-ligands (PMe{sub 3}, PPh{sub 3}, P(p-PhSO{sub 3{sup -}}){sub 3}, etc.), and (b) HyF of propene. For the propylene research, simulations indicated that the linear: branched aldehyde ratio (linear is more desirable) is determined by thermodynamic discrimination of two distinct pathways. Other projects include a theory-experiment study of C-H activation by early transition metal systems, which establishes that weakly-bound adducts play a key role in activity selectivity. By extension, more selective catalysts for functionalization of methane (major component of natural gas) will require better understanding of these adducts, which are greatly affected by steric interactions with the ligands. In the de novo design of Tc complexes, we constructed (and are now testing) a coupled quantum mechanics-molecular mechanics protocol. Initial research shows it to be capable of accurately predicting structure ''from scratch.'' Challenges include conformational, geometric, coordination, spin, and particularly linkage (e.g., Tc-SCN versus Tc-NCS) isomerism. In general, our protocol can rapidly (

Download or read book Transition Metals in Coordination Environments written by Ewa Broclawik and published by Springer. This book was released on 2019-03-16 with total page 532 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the electronic properties of transition metals in coordination environments. These properties are responsible for the unique and intricate activity of transition metal sites in bio- and inorganic catalysis, but also pose challenges for both theoretical and experimental studies. Written by an international group of recognized experts, the book reviews recent advances in computational modeling and discusses their interplay using experiments. It covers a broad range of topics, including advanced computational methods for transition metal systems; spectroscopic, electrochemical and catalytic properties of transition metals in coordination environments; metalloenzymes and biomimetic compounds; and spin-related phenomena. As such, the book offers an invaluable resource for all researchers and postgraduate students interested in both fundamental and application-oriented research in the field of transition metal systems.

Download or read book Mechanistic Studies for Catalytic Transformation of Small Oxygenates on Transition Metals written by Suyash Singh and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Over the past century, heterogeneous catalysis has played a central role in the development of efficient chemical processes for the conversion of fossil resources to fuels and chemicals, and identification of new, sustainable routes to upgrade renewable carbon sources that minimize the ecological footprint. More recently, unprecedented advances in electronic structure theory and related computational methods have provided a major thrust to the efforts that utilize density function theory (DFT) calculations for developing fundamental atomic-level understanding of these processes, and subsequently designing new and improved catalysts. In this dissertation, a combined theoretical and experimental approach is presented to study the reaction mechanisms for the catalytic conversion of formic acid (FA) and propylene oxide on transition metals. An iterative methodology comprising of DFT calculations, reaction kinetics measurements, and mean-field microkinetic modeling is employed to determine the nature of active sites on supported catalysts, explain the experimentally observed trends, and obtain predictions for the surface environment under reaction conditions. A detailed analysis of the DFT derived thermochemistry and kinetics parameters over a wide range of transition metal surfaces is performed to identify the key reactivity descriptors for FA decomposition on transition metal catalysts, and develop semi-empirical linear correlations that are then used to develop a microkinetic modeling based framework for the identification and design of improved (active and selective) bimetallic alloy catalysts. Finally, the possible utilization and applications of these methods and ideas in other key chemical transformations are proposed, and suggestions for future work are included.

Download or read book An Exploration of Mid to High valent Transition Metal Complexes for Application to Catalysis written by Kelly E. Aldrich and published by . This book was released on 2019 with total page 824 pages. Available in PDF, EPUB and Kindle. Book excerpt: The valency or oxidation state of a transition metal in a complex plays a large role in determining the reactivity of the complex. With transition metal chemistry, historically accessible chemistry has often focused on metals in a low oxidation state. However, transformations involving transition metals in high oxidation states are of equal importance in providing complex products for use in consumer products. Expanding the applications and understanding of transition metal complexes in high oxidation states is the focus of the research presented in this dissertation. Fundamental studies of how ligands interact with high valent metals is presented in chapters 2 and 3, where a chromium(VI) model complex has been used to study bonding interactions between this d0 transition metal and phosphine ligands. Practical application of high valent titanium(IV) catalysts to C--N bond forming reactions is presented in chapters 4--6. Finally, chapters 7 and 8 focus on the changes in the character of M--N double bonds, with M=Fe and Ru, as the metal is forced to higher oxidation states. Collectively, these studies demonstrate different approaches to the same general problems and questions of how chemists can better understand and utilize high valent transitions metals to do catalytically-target desired transformations.

Download or read book Research Awards Index written by and published by . This book was released on 1985 with total page 1588 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Toxicology Research Projects Directory written by and published by . This book was released on 1978 with total page 820 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Handbook of Chalcogen Chemistry written by Francesco A. Devillanova and published by Royal Society of Chemistry. This book was released on 2013 with total page 611 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of Chalcogen Chemistry provides an overview of recent developments on the chemistry of the chalcogen group elements (S, Se and Te).

Download or read book Handbook of Chalcogen Chemistry written by Francesco Devillanova and published by Royal Society of Chemistry. This book was released on 2013-07-25 with total page 611 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Handbook of Chalcogen Chemistry: New Perspectives in Sulfur, Selenium and Tellurium provides an overview of recent developments, particularly from the last decade, on the chemistry of the chalcogen group elements (S, Se and Te). While up to a few decades ago, chalcogen chemistry was mainly centred on sulphur, in recent years the research based on Se and Te has increased dramatically, and has created huge scope for the use of compounds based on this type of chemistry. The Handbook is organised into two parts, the first of which deals systematically with the chemistry of chalcogens in relation to other group elements in the periodic table. It also includes an overview of metal-chalcogenides and metal-polychalcogenides. The second part reflects the interdisciplinary nature of chalcogen chemistry and focuses on biological, materials and supramolecular aspects of the field. This Handbook gives a comprehensive overview on recent developments over the last decade and is ideal for researchers in the field.

Download or read book Metal Oxo and Metal Peroxo Species in Catalytic Oxidations written by B. Meunier and published by Springer. This book was released on 2003-09-04 with total page 327 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is a description of the current knowledge on the different metal-oxo and metal-peroxo species involved in catalytic oxidations. The series contains critical reviews of the present position and future trends, and short and concise reports written by the world’s renowned experts.

Download or read book Energy and Water Development Appropriations for 1999 written by United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development and published by . This book was released on 1998 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book INIS Atomindex written by and published by . This book was released on 1986 with total page 956 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Current Organic Chemistry written by and published by . This book was released on 2009 with total page 452 pages. Available in PDF, EPUB and Kindle. Book excerpt: Provides in depth reviews on current progress in the fields of asymmetric synthesis, organometallic chemistry, bioorganic chemistry, heterocyclic chemistry, natural product chemistry, and analytical methods in organic chemistry. Each issue is edited by an appointed Executive Guest Editor

Download or read book Energy and Water Development Appropriations for 1999 Department of Energy fiscal year 1999 budget justifications written by United States. Congress. House. Committee on Appropriations. Subcommittee on Energy and Water Development and published by . This book was released on 1998 with total page 3256 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Machine Learning in Chemistry written by Jon Paul Janet and published by American Chemical Society. This book was released on 2020-05-28 with total page 189 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent advances in machine learning or artificial intelligence for vision and natural language processing that have enabled the development of new technologies such as personal assistants or self-driving cars have brought machine learning and artificial intelligence to the forefront of popular culture. The accumulation of these algorithmic advances along with the increasing availability of large data sets and readily available high performance computing has played an important role in bringing machine learning applications to such a wide range of disciplines. Given the emphasis in the chemical sciences on the relationship between structure and function, whether in biochemistry or in materials chemistry, adoption of machine learning by chemistsderivations where they are important

Download or read book Journal written by American Chemical Society and published by . This book was released on 2001 with total page 1320 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Scientific and Technical Aerospace Reports written by and published by . This book was released on 1995 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Nuclear Science Abstracts written by and published by . This book was released on 1975 with total page 764 pages. Available in PDF, EPUB and Kindle. Book excerpt: