N-Chelating Ruthenium Complexes for Olefin Metathesis
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Solution Overview
Problem
Existing N-chelating ruthenium complexes used as catalysts or (pre)catalysts in olefin metathesis reactions are often latent, requiring elevated temperatures or chemical activation due to strong Ru—N interactions, which slows down the initiation of metathesis reactions.
Innovation Solution
The use of N-chelating ruthenium complexes with at least one aryl substituent in the benzylidene part, which reduces the electron density on the nitrogen atom, leading to higher activity in olefin metathesis reactions without the need for activation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If N-chelating ruthenium complexes are used as catalysts in olefin metathesis reactions, then the catalysts show high functional group tolerance and stability, but the strong Ru—N interaction causes slow initiation rates requiring elevated temperatures or chemical activation
Solution Approach 1:
The patent modifies the electronic parameters of the ruthenium complex by introducing electron-withdrawing groups (such as aryl substituents with nitro, cyano, or carbonyl groups) on the benzylidene ligand. This changes the electron density distribution, reducing electron density on the nitrogen atom and weakening the Ru—N interaction, thereby accelerating initiation while maintaining catalyst stability
2Productivity
If electron-withdrawing groups are introduced to increase initiation rate, then the catalyst becomes more active, but the electron density on the chelating nitrogen decreases which may affect catalyst stability
Solution Approach 1:
The patent applies local quality modification by placing electron-withdrawing groups at specific positions on the benzylidene ligand (ortho or para positions relative to the nitrogen coordination site). This creates a localized electronic effect that reduces electron density on the nitrogen atom without uniformly destabilizing the entire complex, thus balancing initiation rate improvement with catalyst stability maintenance
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
These complexes exhibit high activity in a wide range of olefin metathesis reactions, including ring closing metathesis, cross metathesis, and homometathesis, with improved initiation rates compared to traditional latent catalysts.
Implementation Method 1
The invention relates to the use of N-chelating ruthenium complexes of the general formula 1 as catalysts and/or (pre)catalysts in the olefin metathesis reaction
Data Source
AI summary
The subject matter of the invention is the use of a ruthenium complex of the formula 1, wherein the individual substituents have meanings as indicated in the olefin metathesis reactions description, including a reaction selected from such as ring-closing metathesis (RCM), homometathesis (self-CM) or cross metathesis (CM).