RINGWALK · Ring-walking, metal coordination and aryl-halide oxidative addition
7РП — „Хора“ (Действия „Мария Кюри“)
- Период
- 2008-09-28 → 2010-09-27
- Финансиране от ЕС
- 170 484 €
- Участници
- 1
- Схема
- MC-IIF
Линиите свързват координатора с партньорите.
Накратко на български
Химичните реакции с флуорирани съединения, като например създаването на въглерод-въглеродни връзки чрез катализатори, се анализират в детайли. Това помага за подобряване на ефективността при производството на материали за електрониката, фармацевтиката и слънчевите клетки.
Кратко обяснение, генерирано от езиков модел по текста на CORDIS. Оригиналът е по-долу.
Резултати накратко
Ring-walking, metal coordination and aryl-halide oxidative addition
Fluorinated compounds are widely used in the semiconductor and pharmaceutical industries. Their applications include electronic materials, solvents, lubricants and phase-transfer catalysts. Despite their many applications, their formation is not trivial. In particular, transition-metal catalysed cross-coupling reactions (e.g. Sonogashira, Heck, Suzuki) to generate carbon-carbon bonds with fluorinated substrates are often hampered by the formation of strong metal-carbon bonds and other competitive processes. In 2001, Espinet and Milstein reported Heck catalysis with fluorinated aryl-halides, while the use of non-fluorinated substrates had already been known for four decades. Likewise, it took about two decades after the initial report on the Sonogashira reaction to apply it to fluorinated substrates. One commonly observed by-product of cross-coupling reactions is hydrodehalogenation of fluorinated aryl-halides, which affects the efficiency and selectivity of the overall catalytic process. The Marie Curie fellow, Dr Joyanta Choudhury, obtained detailed mechanistic information regarding some of the key steps involved in the Sonogashira and related cross-coupling reactions with fluorinated aryl-halides. These results have been submitted for publication as a communication. Another related manuscript about the activation of aryl-halides bonds by palladium is in preparation. The research results are most likely applicable to a wide range of processes with fluorinated aryl-halides and platinum-group metals. This Marie Curie project generated also series of new materials which have been used by the fellow to study thin film formation, demonstrate Boolean logic and fabricate solar cells. These results have already been reported: Angew. Chem. Int. Ed. 2010, 49, 4780-4783; J. Am. Chem. Soc. 2010, 132, 9295-9297; J. Am. Chem. Soc. 2010, ASAP DOI: 10.1021/ja104695p. The development of molecular-based systems capable of information processing is a rapidly developing field. Functionality can be rationally designed on the basis of an understanding of the structures involved. Therefore, the role of the molecular structure and reaction parameters on the nature of thin-film growth was studied as well. Our electrochromic films are generated using a versatile two-step assembly method with organic and metal-organic chromophores cross-linked with palladium. The polypyridyl complexes exhibit exponential growth, whereas, under identical conditions, organic chromophores exhibit linear behaviour. The internal film morphology plays a key role in the storage and usage of the palladium, where a more porous structure results in exponential growth. Interestingly, through proper tuning of the reaction conditions, the growth of the molecular assemblies can be controlled, resulting in a changeover from exponential to linear growth. These findings unequivocally demonstrate the importance of both the internal film structure and deposition conditions on the assembly of functional molecular-based films. For additional informatie, see: http://www.weizmann.ac.il/oc/vanderboom/
Текст от CORDIS, на английски · Данни: CORDIS, © Европейски съюз
Цел на проекта
The proposed project deals with the formation of new late transition metal-based stilbene and stilbazole complexes, formed via a series of transformations, including metal-olefin coordination, metal ring-walking, and aryl-halide oxidative addition. This project is related to recently published results (van der Boom, M. E. et al J. Am. Chem. Soc. 2005, 127, 9322; Organometallics, 2006, 25, 3308; Organometallics, 2007, in press; Chem. & Eng. News 2005 Sept. 19,). Our studies indicate that a zerovalent platinum center coordinates to the stilbene carbon-carbon double bond and subsequently walks in the solid state and in solution over the π-system of the stilbene ligand prior to activation of an aryl– halide moiety. The cleavage of the aryl–halide bond is the rate determining step. This model system is an ideal vehicle to observe several organometallic steps in a consecutive manner. We are interested in studying the mechanistic aspects of these reactions, especially the metal ring-walking process. Many challenging questions remain. For example, is it possible by proper ligand design to direct a metal center to a specific molecular site? The proposed research will be conducted by varying the nature of the metal complex precursors (e.g., metal periodic table position, oxidation state, phosphine vs nitrogen ligands, chelating vs non-chelating ligands, …) and by preparation of stilbene and stilbazole ligands. Kinetic studies will be carried out using (variable temp.) NMR and UV/vis spectroscopy. Some of the compounds will be used for crystal engineering (van der Boom et al , M. E. Crys. Growth & Des. 2005, 5, 1671), and coordination-based assembly of intrinsically acentric multilayers (van der Boom, M. E. et al J. Am. Chem. Soc. 2006, 128, 7374). The acquired mechanistic information may be used for the design of new metal-mediated organic reactions and homogeneous catalysis, including arene functionalization, activation of aryl–halides, and cross-coupling reactions.
Оригинален текст от CORDIS (на английски).
Участници
- WEIZMANN INSTITUTE OF SCIENCE · RehovotКоординаторИзраел
Връзки
Данни: CORDIS, © Европейски съюз