Towards Supported Nitrogen Containing Fragments on Silica Surface for Catalytic Applications

الموضوعات

علوم بحتة وطبيعية

الملخص

This thesis shed lights on metal-nitrogen organometallic fragments supported on silica surface for catalytic applications. It Focuses on group IV and V metal transition as a well-defined single-site catalysts, specifically titanium, hafnium, and tantalum to utilize them in the development of selective heterogeneous catalysis for imine metathesis, hydroamination and hydroaminoalkylation of olefins and alkynes. Developing new metal-nitrogen containing fragments by using easily available and abundant precursors which is silica SiO2 and metal amides complexes. Here, we describe metal fragments starting with hafnium-nitrogen fragment. All the catalysts were prepared by reacting homoleptic metal amido of group IV and V with partially dehydroxylated silica. In most cases the resulting surface amido is monopodal and leads to well defined single site catalysts precursors. In particular with Hf we have isolated hafniaaziridine 2.1 [(≡Si-O-)Hf(η2-MeNCH2)(η1-NMe2)(η1-HNMe2)], imido, and amido fragments 2.3 [(≡Si-O-)Hf(=NMe)(η1-NMe2)], and two intermediates the five-membered ring 2.2 [≡Si-O-Hf(HNMe2)(η2-NMeCH2CH(C6H13)CH2)(NMe2)] and 2.4 [(≡Si-O-)Hf(=NCH2Ar) (η1-NMe2)]. For tantalum 3.1 [(≡Si-O-)Ta=NtBu)(η1-NMeEt)2]; we have isolated two intermediates after treating 3.1 catalyst with aniline substrate lead to isolating 3.3 [(≡Si-O-)Ta(η1σ-NEtMe)2(η1σ-NHtBu)(NHC6H10)], and upon treating with 1-octyne lead to isolating 3.2 [(≡Si-O-)Ta(η1σ-NEtMe)2(η2-NtBuC=CC7H13)]. For titanium-nitrogen fragments, we isolated on silica SiO2-200 4.1 [(≡Si-O2-)Ti(NMe2)2 (η1-HNMe2)] and on SiO2-700 the titaniaaziridine 4.2a [≡Si-O-Ti(NMe2)3] 4.2b, [(≡Si-O-)Ti(η2-MeNCH2)(η1-NMe2)(η1-HNMe2)], the imido, and amido fragments 4.4 [(≡Si-O-)Ti(=NMe)(η1-NMe2)], and the five-membered ring intermediate 4.3 [≡Si-O-Ti(HNMe2)(η2-NMeCH2CH(C6H13)CH2)(NMe2)]. Research in this area has led to isolating several intermediates containing nitrogen fragments, this is the strength of surface organometallic chemistry which allows a deeper understanding of catalytic phenomena which could not be approached either in homogeneous catalysis or in classical heterogeneous catalysis. A molecular level characterization of the surface nitrogen containing fragments have been characterized by SOMC tools such as FTIR and EXAFS spectroscopy, elemental analysis, solid-state single and multiple quantum NMR, advanced DNP-SENS and DFT. A catalytic cycle was proposed based not only on the isolation of intermediates but also based on DFT calculations.

روابط وملفات

التعريف والنوع

رقم الوثيقة

fd3e8e2f-b883-44b4-bf0d-716c52a308f4

رقم العقد

0

نوع الوسائط

Crawler

نوع المحتوى

الرسائل العلمية

صيغة المصدر

رسائل دكتوراة

نوع الملف

pdf image

أسماء الملفات

fd3e8e2f-b883-44b4-bf0d-716c52a308f4_1.pdf

بيانات النشر

ألقاب المؤلفين

[{"name_ar":" Jean Marie Basset","title_ar":"اشراف","title_en":"Supervision"},{"name_ar":" Maha A Alrefai Aljuhani","title_ar":"اعداد","title_en":"Preparation"},{"name_ar":"Jérémie D A Pelletier","title_ar":"اشراف","title_en":"Supervision"}]

اللغة

English

المصدر والدورية

اسم المصدر

Towards Supported Nitrogen Containing Fragments on Silica Surface for Catalytic Applications

المحتوى والصفحات

عدد الصفحات

0

كلمات الباحثين

Heterrogenous Catalysis Hydroamination Imine metathesis Hydroaminoalkylation Intermediate seperation SOMC and SOMF

إشراف وإعداد

الإشراف

Jean Marie Basset, Jérémie D A Pelletier

الإعداد

Maha A Alrefai Aljuhani

الاقتباسات الببليوغرافية