Non-d0 Re(V) Alkylidyne Catalysts for Air-Stable Alkyne Metathesis
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Solution Overview
Problem
Current alkyne metathesis catalysts are sensitive to air and moisture, limit substrate compatibility, and require high temperatures, making them difficult to use and store, and are not effective for reactions involving carbonyl or protic functional groups.
Innovation Solution
Development of non-d0 Re(V) alkylidyne complexes that are stable to air and moisture, tolerant of various functional groups, and active at moderate temperatures, enabling efficient alkyne metathesis reactions such as homo-, cross-, ring-closing, and ring-opening metathesis.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If d0 early transition metal alkylidyne complexes are used as catalysts, then catalytic efficiency and substrate scope are improved, but air and moisture sensitivity increases, making them difficult to prepare, use, store, and transport
Solution Approach 1:
The patent changes the oxidation state parameter of the rhenium catalyst from the conventional d0 Re(VII) to a non-d0 Re(V) configuration. This parameter change fundamentally alters the electronic structure, enabling the catalyst to maintain high catalytic activity while achieving remarkable stability toward air and moisture, thus resolving the contradiction between productivity and reliability
Solution Approach 2:
The patent employs composite ligand systems combining phosphine and pyridine ligands with the rhenium center to create a synergistic effect. The specific combination of L1-L6 ligands (including phosphines like PMePh2, PMe2Ph and pyridine derivatives) creates a protective electronic environment that enhances both catalytic performance and environmental stability, allowing the catalyst to function reliably under air and moisture conditions
2Productivity
If d0 early transition metal alkylidyne complexes are used as catalysts, then catalytic activity is enhanced, but tolerance for substrates with carbonyl or protic functional groups decreases
Solution Approach 1:
The patent changes the electronic configuration parameter from d0 to non-d0 (Re(V)), which fundamentally alters the catalyst's interaction with substrates. This parameter change reduces the catalyst's excessive reactivity toward carbonyl and protic groups while maintaining alkyne metathesis activity, thereby expanding substrate compatibility
Solution Approach 2:
The patent introduces local electronic differentiation through the specific ligand environment. The phosphine and pyridine ligands create localized electron density patterns around the rhenium center that selectively stabilize the catalyst against unwanted reactions with carbonyl and protic functional groups while preserving the active site's ability to catalyze alkyne metathesis
3Ease of operation
If inorganic oxide catalysts loaded on silica are used, then ease of handling is improved, but catalytic efficiency decreases, requiring activation at high temperatures
Solution Approach 1:
The patent replaces the heterogeneous inorganic oxide catalyst system with a homogeneous molecular catalyst system. This substitution eliminates the need for high-temperature activation and complex handling procedures associated with heterogeneous catalysts, while providing superior catalytic efficiency through well-defined molecular structure and mechanism
Data Source
AI summary
Non-d0 rhenium(V) alkylidyne catalysts useful for catalyzing alkyne metathesis reactions, such as homo- and cross-metathesis of alkynes or diynes, ring closing metathesis and ring-opening metathesis, methods or use, and preparation thereof. The catalysts are stable to air and moisture and tolerate a variety of functional groups in substrates.