Structure[ edit ] Alkali metal alkoxides are often oligomeric or polymeric compounds, especially when the R group is small Me, Et. In solution, the alkali metal derivatives exhibit strong ion-pairing, as expected for the alkali metal derivative of a strongly basic anion. Structure of the Li4 OBu-t 4 thf 3 cluster, highlighting the tendency of alkoxides to aggregated and bind ether ligands.
Multimetallic Polymerization Catalysis Research in the Agapie laboratory is targeted toward developing new, practical catalysts by using inspiration from biological systems.
Some of the most fascinating catalysts in Nature display complex inorganic cofactors, sometimes in combination with organic cofactors, and perform chemical transformations water reduction and oxidation, carbon dioxide reduction, dinitrogen reduction, dioxygen reduction that are arguably prerequisites for the advance of society in the current context of limiting energy resources and environmental concerns.
Given the scale of the potential applications, we focus on studies of inexpensive and abundant first-row transition metals. To these ends we have developed new methodologies for the synthesis of complex inorganic targets and have performed mechanistic studies to understand the properties and reactivity of these compounds.
Our research focuses on three general topics: What is metathesis of compounds mixed metal oxides as catalysts for water oxidation and O2 reduction in heterogeneous and biological systems, fundamental understanding of the effects of redox inactive metals on the chemistry of mixed metal oxide clusters is important for the rational development of effective catalysts.
Prior to our work, a single high oxidation state complex displaying an oxo bridged redox active — redox inactive heterometallic core had been structurally characterized and studied for redox chemistry, though examples of in situ modulation of reactivity by metal Lewis acids had been reported.
We have developed rational strategies for the synthesis of a series of well-defined heterometallic oxide clusters that have allowed for systematic structure-property studies.
Olefin Metathesis Grubbs Reaction. Olefin Metathesis allows the exchange of substituents between different olefins - a transalkylidenation. This reaction was first used in petroleum reformation for the synthesis of higher olefins (Shell higher olefin process - SHOP), with nickel catalysts under high pressure and high temperatures. Olefin Metathesis Olefin metathesis, or alkene metathesis, is an important process in petroleum refining and in the synthesis of important compounds such as pharmaceuticals. The mechanism of olefin metathesis is related to . It is well established in the literature that compounds containing basic nitrogen atoms are problematic substrates for olefin metathesis. It’s assumed that the basic nitrogen atom coordinates to the metal center and interferes with catalytic activity.
The reduction potentials of these clusters were found to depend linearly on the Lewis acidity of the redox inactive metal. This finding has applications in rationally tuning the reduction potentials of metal oxide clusters to match the thermodynamic requirements of the desired redox transformations.
Mechanistic studies have provided insights into the mechanism of cluster assembly and O- and H-atom transfer. Synthesized complexes have been studied by collaborators for spectroscopic benchmarking relative to the biological system. In the context of small molecule activation, the ability of protein active sites to transfer electrons and protons is instrumental for selectivity and high reaction rates.
We have developed new molecular architectures for multimetallic complexes of redox active metals and monometallic complexes of non-innocent ligands.
Although non-innocent ligands have often been employed to transfer electrons or protons, pendant groups that transfer both are relatively rare, despite the biological precedent.
Moieties such as catechol and hydroquinone are envisioned to act as reservoirs of both electrons and protons, if placed in proximity of metals orthogonally to the arene plane. Toward that end, hemi-labile arene ligands with pendant donors have been employed for their versatility and potential to lower reaction barriers by accommodating several metal binding modes.
New types of bimetallic reactivity C-C coupling with Nicatalysts Mo catalyzed ammonia-borane dehydrogenationand mechanistic insights metal mediated aryl C-O bond activation, H-transfer to arene have been achieved.
The functionalized versions of these systems, with catechol and hydroquinone moieties, bind metals while retaining the protonated state.
Therefore, they can deliver not only electrons, but also protons to substrates such as O2, clearly showing the potential of such motifs for metal mediated multi-electron and multi-proton chemistry. The insertion polymerization of polar monomers has been a significant challenge in polyolefin synthesis.
Bimetallic catalysts have been proposed as candidates to address this problem, but the molecular design of many of the known systems has provided limited insight into the reaction mechanism due to high flexibility or distant placement of metals.
We have prepared bimetallic complexes with rigid organic linkers that lock the metals centers at well-defined positions. Our studies have revealed a mechanism of bimetallic cooperativity that contrasts with other proposals in the literature, with reactivity being affected by the steric interaction between coordinated ligands.All Mechanisms: Displaying mechanisms: Alicyclic- electrophilic addition of bromine to cyclohexene (bromonium ion opening) Alicyclic- Grobb rearrangement.
A hypertext guide to Organometallic Chemistry, useful as a study aid or introduction to the subject. It is well established in the literature that compounds containing basic nitrogen atoms are problematic substrates for olefin metathesis. It’s assumed that the basic nitrogen atom coordinates to the metal center and interferes with catalytic activity.
Structure. Alkali metal alkoxides are often oligomeric or polymeric compounds, especially when the R group is small (Me, Et). The alkoxide anion is a good bridging ligand, thus many alkoxides feature M 2 O or M 3 O linkages.
In solution, the alkali metal derivatives exhibit strong ion-pairing, as expected for the alkali metal derivative of a strongly basic anion. Here is a collection of study cards for my AP and General Chemistry classes. There are four cards per page. Each set of cards is saved as an Adobe Acrobat® file.
Olefin Metathesis in Organic Synthesis Wendy Jen MacMillan Group Meeting January 17, I. Well-defined alkene metathesis catalysts II. Applications of Olefin Metathesis A.
Ring closing metathesis B. Cross metathesis C. Ring opening metathesis Recent Reviews: Furstner, A.