Selectivity Of Metathesis Reactions Catalyzed By Supported Complexes Of Group Vi

الموضوعات

علوم بحتة وطبيعية

الملخص

The general objective of this thesis is the analysis of selective reactions for group VI grafted metal complexes via methods and principles of SOMC. For this objective, three approaches have been chosen. The first chapter is an introduction to the topic of selectivity in catalysis, emphasizing heterogeneous catalysis and more specifically the different approaches to support catalysts on surfaces. The concept of catalysis by design is introduced as a new way to use the surface as a ligand. Chapter 2 presents the results of a library of well-defined catalysts of group VI with identical catalytic functionality, but different ligand environment. The results reveal, thatmetal-carbynes are able to switch their catalytic reactivity based on the substrate that they are contacted with. The difference in reaction mechanisms and the differingre activities towards the substrates are presented. It can be concluded that the classical ROMP is selectively achieved with cyclic alkene substrates leading to polymers whereas cyclic alkanes yield exclusively higher and lower homologues of the substrate without polymeric products. Chapter 3 presents the study of olefin metathesis of cis-2-pentene with metal-carbynes of group VI, where the selectivity of the catalyst library towards yield of cis-/trans products is analyzed. It is presented, that the ligand environment of the catalysts is showing an influence in the selectivity. Rates of cis/trans isomerization of the products are high and are approaching thermodynamic equilibrium at high conversion. Product isomerization, thermodynamic equilibrium and reactivity differences between liquid phase and gas phase products are analyzed. Chapter 4 presents the full characterization of tungsten-hydrides by selective transformation into tungsten-hydroxides. These newly discovered well-defined tungsten hydroxides are fully characterized by ICP, TEM, DRIFT, double quantum and triple quantum solid-state NMR. The presented results allow to predict that tungsten-hydride son KCC-1700 are present as two distinct species. Catalysis results with cyclooctane show, that due to burial of the complexes in the KCC-1700 surface the tungsten-hydrides are less active towards cyclic alkane metathesis reactions with bulky cyclooctane than the metalcarbyne complexes. Chapter 5 is giving a conclusion of results and an outlook for catalytic applications of the generated tungsten-hydroxides of chapter 4.

روابط وملفات

التعريف والنوع

رقم الوثيقة

095ef3c8-cdea-41af-9d94-1bd9522dc2ae

رقم العقد

0

نوع الوسائط

Crawler

نوع المحتوى

الرسائل العلمية

صيغة المصدر

رسائل دكتوراة

نوع الملف

pdf text

أسماء الملفات

2021213_1.pdf

بيانات النشر

ألقاب المؤلفين

[{"name_ar":" Jean-Marie Basset","title_ar":"اشراف","title_en":"Supervision"},{"name_ar":" Wiebke Wackerow","title_ar":"اعداد","title_en":"Preparation"}]

اللغة

English

المصدر والدورية

اسم المصدر

Selectivity Of Metathesis Reactions Catalyzed By Supported Complexes Of Group Vi

المحتوى والصفحات

عدد الصفحات

0

كلمات الباحثين

heterogeneous catalysis SOMC single-site alkane metathesis metallo carbynes tungsten hydrides

إشراف وإعداد

الإشراف

Jean-Marie Basset

الإعداد

Wiebke Wackerow

الاقتباسات الببليوغرافية