Supported Cationic Ruthenium Catalysts for Efficient Surface Heterogenization
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Solution Overview
Problem
Existing methods for preparing well-defined ruthenium catalysts on surfaces are complex and inefficient, lacking effective strategies for heterogenizing ruthenium catalysts onto oxides.
Innovation Solution
A method involving the use of silylium-capped surfaces to abstract halide ions from commercially available ruthenium catalysts, forming cationic ruthenium catalysts that form ion-pairs with anionic supports, creating a catalyst composition that is highly active in olefin metathesis reactions, with the cationic ruthenium catalysts, which are capable of catalyzing olefin metathesis reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to prepare ruthenium catalysts on surfaces, then the catalysts can be synthesized, but the preparation methods are complex and inefficient
Solution Approach 1:
The patent applies preliminary action by first generating a cationic ruthenium species with a labile ligand before the actual catalyst formation step. The cationic Ru complex is prepared in advance with a leaving group (X) that can be easily displaced, allowing the subsequent heterogenization step to proceed efficiently without requiring complex multi-step syntheses. This pre-preparation of the cationic species simplifies the overall process.
Solution Approach 2:
The patent uses an intermediary approach by introducing a support material with nucleophilic sites (such as oxide surfaces with oxygen atoms) that mediates the formation of the catalyst. The support acts as an intermediary between the cationic ruthenium species and the final catalyst structure, facilitating ligand displacement and catalyst anchoring through simple ion-pair interactions rather than complex covalent bonding sequences.
2Reliability
If multi-step syntheses are used to access materials containing reactive groups that bind ruthenium compounds, then well-defined ruthenium catalysts can be formed, but the process becomes inefficient
Solution Approach 1:
The patent segments the catalyst formation process into two distinct stages: (1) preparation of the cationic ruthenium species with a labile ligand in solution, and (2) transfer to the support material where the ligand is displaced. This segmentation allows each step to be optimized independently - the cationic complex can be prepared using well-established homogeneous catalysis methods, while the support interaction provides a simple, reliable anchoring mechanism without requiring complex multi-step syntheses.
3Reliability
If protonolysis of M-X group by OH group on oxide surface is used, then well-defined organometallic can be generated, but this method has limitations for ruthenium catalysts
Solution Approach 1:
The patent changes the key parameter of the ruthenium complex from a neutral or anionic species to a cationic species with a labile ligand. This parameter change enables the ruthenium catalyst to interact with the oxide support through ion-pair formation rather than requiring protonolysis. The cationic character allows the ruthenium complex to be stabilized on the support surface while maintaining catalytic activity, overcoming the limitations of the conventional protonolysis method for ruthenium systems.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The cationic ruthenium catalysts are at least twice as active as neutral homogeneous catalysts, demonstrating high turnover numbers and frequencies in olefin metathesis reactions.
Implementation Method 1
A method involving the use of silylium-capped surfaces to abstract halide ions from commercially available ruthenium catalysts, forming cationic ruthenium catalysts that form ion-pairs with anionic supports
Implementation Method 2
the cationic ruthenium catalysts, which are capable of catalyzing olefin metathesis reactions
Implementation Method 3
The cationic Ru catalyst has structure of Formula I wherein X is absent, halogen, O(O═)CRt or —ORx
Data Source
AI summary
Certain embodiments of the invention provide a supported cationic Ru catalyst that is highly active in catalyzing olefin metathesis. Certain embodiments of the invention also provide a method of making a supported cationic Ru catalyst described herein, comprising contacting a Ru catalyst with a silylium-capped support.