Synthesis and Coordination Chemistry of Anionic Pnictogenylborane Derivatives PDF Download

Author: Tobias Kahoun
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ISBN:
Category :
Languages : en
Pages :

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Author: Jonathan William Dube
Publisher:
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Languages : en
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Traditionally low coordinate and low oxidation state main group compounds are isolated utilizing hard anionic donors based on carbon and nitrogen based ligands. Conversely, employing anionic phosphines for this role has been essentially unexplored. In this context, this dissertation describes the synthesis of a number of main group complexes, ranging from group 13 to group 15, utilizing the bis(phosphino)borate ligand class in a supporting role. The remote anionic borate backbone renders the complexes zwitterionic and provides access to unique compounds that possess structures, and exhibit onwards reactivity, that is very different to the analogous compounds stabilized with neutral phosphines. For example, chapter two describes the stabilization of formally positively charged triel ({Ga2I4}2+) and tetrel ({GeCl}+ and {SnCl}+) fragments via common low oxidation state precursors. These structures have no precedent with neutral phosphines and represent a stable and isolable main group element source that is ready for onwards chemistry. For the group 14 compounds, upon removal of the chloride substituent the reactive tetrel centre quantitatively inserts into the ligand backbone. Zwitterionic group 15 compounds were prepared in good yields exploiting known redox chemistry and possess a pnictogen atom (Pn = P, As) in the unusual +1 oxidation state (Chapter 3). The anionic backbone is shown to be critical in accessing the coordination chemistry of these compounds as there are very few examples of the traditional cationic variants being used in subsequent transformations. Both pnictogen proligands form isolable coordination compounds with chromium, molybdenum, tungsten, and iron carbonyl reagents (Chapter 4) while rhodium, palladium, and mercury complexes are also isolated with the phosphorus derivative (Chapter 5). This diverse range of products represents the first such series of transition metal complexes for these types of Pn(I) compounds. The highlight of the thesis is the discovery that the phosphorus proligand acts as a 4-electron -type ligand to two gold, cobalt, or platinum centres simultaneously. Such coordination chemistry is unprecedented and provides the first experimental evidence for the P(I) compound to be described as a phosphanide-type bonding arrangement. These novel structures further underscore the importance of the borate backbone in synthesizing compounds that have otherwise not been observed. Throughout the thesis all of the compounds were fully characterized using a range of solution and solid-state techniques, including single crystal X-ray crystallography, allowing for a detailed data comparison.

Author: Andrew Jolleys
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ISBN:
Category :
Languages : en
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The reaction of imidoyl chlorides IMC1-9 with lithium [beta]-diketiminates Li(BDKx) (x = iPr, iPr2, tBu, Me3, iPr2/OMe) yields [beta]-triketimines L1-16 which represent a new class of facially-coordinating neutral tridentate nitrogen ligands. The synthetic route is highly modular, allowing for wide variation of substitution patterns and thus fine control over the steric demands of the ligands. In all but two examples (L11 and L12) the [beta]-triketimines exist in solution either solely as their enamine-diimine tautomers, or as equilibrium mixtures of the two. The processes of solution-phase equilibration have been studied by NMR spectroscopy. The molecular structures of L1, L10 and L11 are presented, and for each case a single differing tautomer or isomer is observed exclusively. The majority of the ligands yield fac-(L)M(CO)3 adducts upon reaction with group 6 metal carbonyls, except in cases of extreme steric bulk. The [beta]-triketimines are relatively weak [sigma]-donors, as determined by the CO stretching frequencies in (L)M(CO)3. The molecular structures of the isomorphous pair (L1)M(CO)3 (M = Cr, Mo) reveal porous infinite network arrangements generated by aryl-aryl and CH--OC interactions. The direct reaction of [beta]-triketimines with ZnCl2 in most cases gives [(L)ZnCl]2[Zn2Cl6] complexes, whilst in the presence of either NaBArF4 or AgOTf the corresponding [(L)ZnCl][BArF4] and [(L)ZnCl][OTf] species are obtained. The complexes invariably feature four-coordinate, cationic zinc centres, except in the case of [([eta]4-L16)ZnCl][BArF4] where a five-coordinate complex is formed by additional coordination of a single ligand methoxy group. The reaction of [(L)ZnCl][BArF4] with TlOEt yielded not the desired zinc alkoxides, but novel [(L)Tl][BArF4] complexes, the solid-state structures of which display thallophilic interactions. The direct reaction of L8 and L10-12 with NiBr2(DME) gives the corresponding four-coordinate [(L)NiBr]2[NiBr4] complexes, whereas the products obtained with weakly-coordinating anions are dependent on the ligand bulk and the size of the anion. With the large BArF4- ion the formation of the five-coordinate dimeric [{(L)Ni([mu]-Br)}2][BArF4]2 (L = L1, L3, L5, L7, L8, L12) is strongly favoured, except for the bulkiest ligands where the four-coordinate [(L)NiBr][BArF4] (L = L10, L11) are obtained. The smaller triflate ion generally favours the formation of [(L)NiBr][OTf] (L1, L8, L10-12) except in the case of [{(L)Ni([mu]-Br)}2][OTf]2 (L = L3, L5). L15 and L16 act invariably as tetradentate donors to Ni(II), yielding the five-coordinate [([eta]4-L)NiBr][X] (X = BArF4, OTf) and [([eta]4-L16)NiBr]2[NiBr4]. The very bulky L6 coordinates in a bidentate mode to Ni(II), giving the four-coordinate [([eta]2-L6)NiBr(THF)][BArF4] and ([eta]2-L6)NiBr2. [{(L)Ni([mu]-Br)}2][BArF4]2 (L = L3, L5, L7), [{(L)Ni([mu]-Br)}2][OTf]2 (L = L3, L5), [([eta]2-L6)NiBr(THF)][BArF4] and ([eta]2-L6)NiBr2 show moderate catalytic activity for the polymerisation of ethylene in combination with MAO. All other complexes tested are inactive, either due to steric factors or the inability of certain [beta]-triketimines to support catalytically active square-planar Ni(II) species. A proposed mechanism for catalyst activation is presented. Elastomeric polyethylene of very low crystallinity is obtained, with branching rates in the range 43-84 branches per 1000 C. 13C NMR spectroscopy reveals the presence of all short-chain branches from methyl to hexyl, as well as longer branches and pairs of branches.

Author: Olaf Kühl
Publisher: Springer Science & Business Media
ISBN: 3540791183
Category : Science
Languages : en
Pages : 138

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Nuclear Magnetic Resonance is a powerful tool, especially for the identification of 1 13 hitherto unknown organic compounds. H- and C-NMR spectroscopy is known and applied by virtually every synthetically working Organic Chemist. Con- quently, the factors governing the differences in chemical shift values, based on chemical environment, bonding, temperature, solvent, pH, etc. , are well understood, and specialty methods developed for almost every conceivable structural challenge. Proton and carbon NMR spectroscopy is part of most bachelors degree courses, with advanced methods integrated into masters degree and other graduate courses. In view of this universal knowledge about proton and carbon NMR spectr- copy within the chemical community, it is remarkable that heteronuclear NMR is still looked upon as something of a curiosity. Admittedly, most organic compounds contain only nitrogen, oxygen, and sulfur atoms, as well as the obligatory hydrogen and carbon atoms, elements that have an unfavourable isotope distribution when it comes to NMR spectroscopy. Each of these three elements has a dominant isotope: 14 16 32 16 32 N (99. 63% natural abundance), O (99. 76%), and S (95. 02%), with O, S, and 34 14 S (4. 21%) NMR silent. N has a nuclear moment I = 1 and a sizeable quadrupolar moment that makes the NMR signals usually very broad and dif cult to analyse.

Author: Christian Joachim
Publisher: Springer Nature
ISBN: 303056777X
Category : Science
Languages : en
Pages : 235

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This book presents mechanics miniaturization trends explored step by step, starting with the example of the miniaturization of a mechanical calculator. The ultra-miniaturization of mechanical machinery is now approaching the atomic scale. In this book, molecule-gears, trains of molecule-gears, and molecule motors are studied -one molecule at a time- on a solid surface, using scanning probe manipulation protocols and in solution as demonstrated in the European project "MEMO". All scales of mechanical machinery are presented using the various lithography techniques currently available, from the submillimeter to the nanoscale. Researchers and nanomechanical engineers will find new inspirations for the construction of minute mechanical devices which can be used in diverse hostile environments, for example under radiation constraints, on the surface membrane of a living cell or immersed in liquid. The book is presented in a format accessible for university students, in particular for those at the Master and PhD levels.

Author: Hai-Bo Yang
Publisher: Royal Society of Chemistry
ISBN: 1782628584
Category : Science
Languages : en
Pages : 304

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A comprehensive overview of metallomacrocycles from designing complex functional metallosupramolecular systems to their applications.

Author: Evamarie Hey-Hawkins
Publisher: John Wiley & Sons
ISBN: 3527819134
Category : Technology & Engineering
Languages : en
Pages : 421

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Provides complete and undiluted knowledge on making inorganic polymers functional. This comprehensive book reflects the state of the art in the field of inorganic polymers, based on research conducted by a number of internationally leading research groups working in this area. It covers the synthesis aspects of synthetic inorganic polymers and looks at multiple inorganic monomers as building blocks, which exhibit unprecedented electronic, redox, photo-emissive, magnetic, self-healing and catalytic properties. It also looks at the applications of inorganic polymers in areas such as optoelectronics, energy storage, industrial chemistry, and biology. Beginning with an overview of the use of smart inorganic polymers in daily life, Smart Inorganic Polymers: Synthesis, Properties and Emerging Applications in Materials and Life Sciences goes on to study the synthesis, properties, and applications of polymers incorporating different heteroelements such as boron, phosphorus, silicon, germanium, and tin. The book also examines inorganic polymers in flame-retardants, as functional materials, and in biology. An excellent addition to the polymer scientists' and synthetic chemists' toolbox Summarizes the state of the art on how to make and use functional inorganic polymers, from synthesis to applications Edited by the coordinator of a highly funded European community research program (COST action) that focuses specifically on the exploration of inorganic polymers Features contributions from top experts in the field Aimed at academics and industrial researchers in this field, Smart Inorganic Polymers: Synthesis, Properties and Emerging Applications in Materials and Life Sciences will also benefit scientists who want to get a better overview on the state-of-the-art of this rapidly advancing area.

Author: Cheng-Yong Su
Publisher:
ISBN: 9789811217791
Category : Science
Languages : en
Pages : 550

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The construction of catalysts by supramolecular forces has recently become a powerful tool and the role of noncovalent interactions can assist in designing new tools for the construction of effective and selective catalytic systems. It is unquestionably, vastly important to understand how different noncovalent interactions can be controlled or manipulated under appropriate reaction conditions. Supramolecular catalysts have had a tremendous impact on the syntheses of both chemical commodities and fine chemicals over the last 50 years, leading to the discovery of new reactions that were previously deemed impossible. This means that supramolecular chemistry plays a predominant role in accelerating or understanding chemical reactions.This book which addresses the above points is written by some of the leading contributors in this field and is intended for graduate students, researchers and academics working in supramolecular chemistry, organic chemistry, inorganic chemistry, and physical chemistry as well as researchers with an interest in the area of catalysis. The authors give examples illustrating the growth of the field, especially with special emphasis on new results published over the last decade. They also provide an explanation of fundamentals and topical research.

Author: Taku Onishi
Publisher: Springer Nature
ISBN: 9811500061
Category : Science
Languages : en
Pages : 547

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This book collects recent topics of theoretical chemistry for advanced nanomaterials from the points of view of both computational and experimental chemistry. It is written for computational and experimental chemists, including undergraduate students, who are working with advanced nanomaterials, where collaboration and interplay between computation and experiment are essential. After the general introduction of nanomaterials, several computational approaches are explained in Part II. Each chapter presents not only calculation methods but also concrete calculation results for advanced nanomaterials. Hydride ion conducting nanomaterials, high-k dielectric nanomaterials, and organic electronics are focused on. In Part III, the interplay between computational and experimental approaches is explained. The chapters show calculation results, combined with corresponding experimental data. Dimensionality of nanomaterials, electronic structure of oligomers and nanorods, carbon nanomaterials, and the electronic structure of a nanosized sandwich cluster is looked at carefully. In Part IV, functionality analysis is explained from the point of view of the experimental approach. The emphasis is on the mechanism of photoluminescence and hydrogen generation using silicon nanopowder, the superionic conducting mechanism of glass ceramics, nanoclusters formation on the surface of metal oxides, and the magnetic property of an organic one-dimensional nanochannel. Finally, forthcoming theoretical methods for excited states and quantum dynamics are introduced in Part V.

Author: John F. Hartwig
Publisher:
ISBN:
Category : Science
Languages : en
Pages : 1172

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Based on Collman et al.'s best-selling classic book, Principles and Applications of Organotransition Metal Chemistry, Hartwig's text consists of new or thoroughly updated and restructured chapters and provides an in-depth view into mechanism, reaction scope, and applications. It covers the most important developments in the field over the last twenty years with great clarity with a selective, but thorough and authoritative coverage of the fundamentals of organometallic chemistry, the elementary reactions of these complexes, and many catalytic processes occurring through organometallic intermediates, making this the Organotransition Metal Chemistry text for a new generation of scientists.