Hydrogen cleavage by solid-phase frustrated Lewis pairs.

Area of Science:

• Heterogeneous catalysis
• Organometallic chemistry
• Materials science

Background:

• Frustrated Lewis pairs (FLPs) are crucial for small molecule activation, but homogeneous systems can be challenging to separate and recycle.
• Developing solid-phase analogs (s-FLPs) offers potential advantages in catalyst recovery and process simplification.
• Efficient methods for synthesizing and activating s-FLPs are needed to broaden their applicability.

Purpose of the Study:

• To report the direct synthesis of a novel solid-phase frustrated Lewis pair (s-FLP).
• To investigate the reactivity of the synthesized s-FLP with molecular hydrogen (H2).
• To demonstrate the capability of the s-FLP for heterolytic H-H bond cleavage.

Main Methods:

• Direct synthesis of a silica-supported Lewis acid, [bond: SiOB(C6F5)2] (s-BCF).
• Combination of the s-BCF with a Lewis base, tri-tert-butylphosphine ((t)Bu3P), to form the s-FLP.
• Reaction of the s-FLP with H2 under mild conditions to observe H-H bond cleavage.

Main Results:

• Successful direct synthesis of the solid-phase frustrated Lewis pair [[bond: SiOB(C6F5)2][(t)Bu3P].
• Observation of heterolytic H-H bond cleavage upon reaction with H2.
• Formation of the protonated phosphonium and borate species: [[bond: SiOB(H)(C6F5)2][(t)Bu3PH].

Conclusions:

• The study demonstrates a viable method for creating solid-phase frustrated Lewis pairs.
• The synthesized s-FLP effectively activates H2 via heterolytic cleavage under mild conditions.
• This work opens avenues for developing recyclable and heterogeneous catalytic systems for hydrogenation and other reactions.