Cyclic Silylene Ligand Metal Complexes for Stable Hydrosilylation
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Solution Overview
Problem
Current hydrosilylation reactions face challenges with platinum catalysts due to high costs, rarity, instability, and the formation of insoluble colloids, which reduce catalyst efficiency and result in undesirable side reactions and aesthetically unsatisfactory products.
Innovation Solution
Development of metal complexes with cyclic silylene ligands stabilized by Lewis bases, specifically featuring a sila-cyclopropylidene structure and a Lewis base donating an electron doublet to the silicon atom, which form stable catalysts that can be used in lower quantities without forming colloids and promoting side reactions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If platinum catalysts are used for hydrosilylation reactions, then the reaction can be catalyzed effectively, but the catalyst is expensive, rare, and unstable leading to colloid formation
Solution Approach 1:
The patent changes the chemical parameters of the catalyst by developing metal complexes with cyclic silylene ligands stabilized by Lewis bases. This modifies the electronic and steric properties of the catalyst, improving stability while maintaining activity. The specific parameter changes include the introduction of stabilized silylene ligands with Lewis base donors, which alter the catalyst's electronic structure and prevent decomposition into colloids.
Solution Approach 2:
The patent creates composite catalyst systems by combining metal centers (Pt, Pd, Ni, Rh, Ru, Os, or Ir) with cyclic silylene ligands that are themselves stabilized by Lewis bases. This multi-component composite structure synergistically combines the catalytic activity of the metal with the stability provided by the stabilized silylene ligand system, resolving the contradiction between activity and stability.
2Productivity
If platinum catalysts are used, then hydrosilylation reactions proceed, but undesirable side reactions occur including isomerization and hydrogenation
Solution Approach 1:
The patent applies local quality by designing ligands with specific electronic and steric properties that create a localized catalytic environment. The cyclic silylene ligands with Lewis bases provide a specific electronic environment around the metal center that favors hydrosilylation while disfavoring isomerization and hydrogenation. This localized modification of the catalyst's electronic structure at the active site enables selective catalysis.
3Speed
If larger quantities of catalyst are used, then reaction speed is maintained, but cost increases and colloid formation is exacerbated
Solution Approach 1:
The patent develops catalysts that are more stable and can be used in smaller quantities, effectively replacing the need for large amounts of expensive platinum catalysts. The stabilized metal complexes maintain their activity over longer periods and at lower concentrations, reducing both the quantity of precious metal required and the frequency of catalyst replacement.
4Productivity
If conventional catalysts are used, then reactions proceed, but products are colored and aesthetically unsatisfactory due to colloid formation
Solution Approach 1:
The patent converts the potential harm of metal catalyst decomposition into a benefit by designing stabilized metal complexes that resist decomposition. The stabilized cyclic silylene ligands prevent the formation of colloidal particles that cause discoloration, while the metal center maintains its catalytic function. This transforms the potential harmful decomposition pathway into a stable, productive catalytic cycle.
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 metal complexes enable efficient hydrosilylation reactions with reduced catalyst usage, maintaining reaction yield and speed while preventing colloid formation and side reactions, resulting in stable and aesthetically acceptable products.
Implementation Method 1
a Lewis base donating an electron doublet to the atom of silicon of said cyclic silylene structure
Implementation Method 2
Hydrosilylation of unsaturated compounds is carried out by catalysis. Typically, the suitable catalyst for this reaction is a platinum catalyst.
Data Source
AI summary
The present invention concerns a metal complex comprising at least one metal atom chosen from the metals of columns (8, 9) and (10) of the periodic table and one or a plurality of ligands, characterised in that at least one ligand comprises a cyclic silylene structure and a Lewis base that donates an electron pair to the silicon atom of said cyclic silylene structure. These metal complexes are particularly suitable for use as a catalyst, in particular for hydrosilylation.