Cationic Germanium(II) Catalysts for Air-Stable Hydrosilylation

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Solution Overview

Problem

Noble metal-free catalysts for hydrosilylation are sensitive to air and moisture, requiring complex handling and synthesis, limiting their technical applicability due to instability and accessibility issues.

Innovation Solution

Cationic germanium(II) compounds are used as catalysts, which are stable in air and can catalyze hydrosilylations in the presence of oxygen, offering a simpler synthesis route and improved stability compared to their silicon counterparts.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Reliability

If noble metal-free catalysts (such as heterocyclic germylenes with phosphorus and nitrogen groups) are used for hydrosilylation, then the cost is reduced and precious metal dependency is eliminated, but the catalysts become extremely sensitive to air and moisture, requiring special handling measures and complex multi-stage syntheses

Engineering Contradiction:

Improvecatalyst stabilityVSAvoidsynthesis complexity and handling complexity

Core Design Contradiction:

ReliabilityVSDevice complexity

Solution Approach 1:

The patent changes the chemical parameters of the catalyst system by using cationic germanium(II) compounds with specific anions (tetrafluoroborate, hexafluorophosphate, perfluoroethylsulfonate) instead of traditional neutral germylenes. This parameter change results in catalysts that are stable in air and moisture while maintaining catalytic activity, eliminating the need for complex inert atmosphere handling and simplifying synthesis procedures

Inventive Principle:

Principle #35Parameter changes

Solution Approach 2:

The patent employs composite catalyst systems consisting of cationic germanium(II) centers paired with specific counterions (BF4-, PF6-, CF3SO3-). This composite approach creates a synergistic effect where the cationic germanium species provides catalytic activity while the stable anions confer air and moisture stability, resolving the contradiction between reactivity and stability

Inventive Principle:

Principle #40Composite materials

2Ease of manufacture

If heterocyclic germylenes with phosphorus and nitrogen groups are used as catalysts, then hydrosilylation can proceed without precious metals, but the catalysts decompose rapidly in air and require exclusion of air and moisture

Engineering Contradiction:

Improvecatalyst accessibilityVSAvoidsensitivity to air and moisture

Core Design Contradiction:

Ease of manufactureVSObject-affected harmful factors

Solution Approach 1:

The patent develops catalysts that can be prepared from readily available starting materials through simple one-stage syntheses. The cationic germanium(II) compounds can be generated in situ and used immediately, eliminating the need for complex pre-synthesis and special storage conditions. This makes the catalysts practically accessible while maintaining stability in air

Inventive Principle:

Principle #27Cheap short-living objects (Disposable)

Solution Approach 2:

The patent uses halide abstractors (such as AgBF4, AgPF6, or Ph3PAuBF4) as intermediaries to convert readily available germanium halides into the active cationic germanium(II) species. This intermediary step simplifies the overall synthesis by using commercially available materials and avoiding complex multi-stage procedures, while the resulting catalysts are stable in air

Inventive Principle:

Principle #24Intermediary (Mediator)

3Ease of operation

If silicon(II) compounds are used as catalysts for hydrosilylation, then the synthesis can be simplified, but the compounds decompose very rapidly in air and cannot be used under ambient conditions

Engineering Contradiction:

Improveoperational simplicityVSAvoidstability in air

Core Design Contradiction:

Ease of operationVSStability of the object's composition

Solution Approach 1:

Instead of using neutral or anionic germanium species that would be stable but less active, the patent inverts the approach by using cationic germanium(II) compounds. The positive charge on the germanium center enhances its Lewis acidity and catalytic activity, while the choice of stable counterions (BF4-, PF6-, CF3SO3-) provides air and moisture stability, achieving both high reactivity and stability simultaneously

Inventive Principle:

Principle #13The other way round (Inversion)

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 use of cationic germanium(II) compounds provides a stable and efficient catalytic system for hydrosilylation reactions, overcoming the limitations of noble metal-free catalysts by allowing reactions to occur in air and simplifying their synthesis, thus enhancing their technical viability.

Implementation Method 1

cationic germanium(II) compounds catalyze hydrosilylations in the presence of oxygen

Methodology Applied

Scientific EffectCatalysis: Catalysis

Data Source

PatentEP3966217B1Cationic germanium (II) compounds, process for preparing same, and their use as catalysts in hydrosilylation

Publication Date: 2023.08.02 WACKER CHEMIE AG

AI summary

The subject matter of the present invention is a mixture M containing (a) at least one compound A, selected from (a1) a compound of general formula (I), and/or (a2) a compound of general formula (I'); and (b) at least one compound B, selected from (b1) a compound of general formula (II), and/or (b2) a compound of general formula (II'), and/or (b3) a compound of general formula (II''); and (c) at least one compound C, selected from cationic germanium (II) compounds of general formula (III).