Hydrogen splitting at a single phosphorus centre and its use for hydrogenation

Area of Science:

• Main-group chemistry
• Homogeneous catalysis
• Organometallic chemistry

Background:

• Transition-metal complexes dominate catalytic processes.
• Main-group compounds offer potential alternatives to transition metals in catalysis.
• Catalytic hydrogenation using main-group compounds remains challenging despite some dihydrogen activation successes.

Purpose of the Study:

• To synthesize and characterize a novel, geometrically constrained phosphenium cation.
• To investigate the dihydrogen activation capabilities of this main-group compound.
• To evaluate its potential as a catalyst for hydrogenation reactions.

Main Methods:

• Synthesis and isolation of a phosphenium cation featuring a 2,6-bis(o-carborano)pyridine pincer ligand.
• Characterization of the synthesized cation.
• Testing the cation's ability to activate H-H bonds via oxidative addition and catalyze hydrogenation of unsaturated systems.

Main Results:

• Successful synthesis and full characterization of the phosphenium cation.
• Demonstration of H-H bond activation by oxidative addition at a single P(III) cationic center, forming a dihydrophosphonium cation.
• Catalytic hydrogenation of C=C double bonds and fused aromatic systems using the phosphenium cation.

Conclusions:

• The reported phosphenium cation can activate H2 at a single main-group center.
• This main-group compound effectively catalyzes hydrogenation reactions, mimicking transition metals.
• Phosphorus-based main-group compounds show significant promise as metallomimetic hydrogenation catalysts.