trimethylphosphine

Trimethylphosphine, also known as trimethylphosphan, is an organophosphorus compound with the formula PMe3 (C3H9P). It is a tertiary phosphine that is colorless and volatile, and it is highly reactive toward oxygen and moisture. In air, it slowly or rapidly oxidizes to trimethylphosphine oxide (OPMe3), so it is typically handled under inert atmosphere.

As a ligand, PMe3 is a strong Lewis base due to its lone pair on phosphorus and is a relatively strong σ-donor. It forms coordination complexes with many transition metals and is widely used in homogeneous catalysis. Its electronic properties make it a more electron-rich donor than many aryl phosphines, contributing to activity in reactions such as hydroformylation, hydrogenation, carbonylation, and cross-coupling processes.

Preparation and handling are conducted under strictly controlled conditions. A common laboratory route involves the reaction of phosphorus trichloride with methyl Grignard reagents, followed by workup to give PMe3. Alternative routes involve deoxygenation of related phosphine oxides or related phosphorus precursors. Due to its air sensitivity and toxicity, trimethylphosphine is typically stored and used under an inert atmosphere and away from oxidizers.

Safety and hazards are important considerations. Trimethylphosphine is toxic and flammable; exposure can irritate the respiratory tract and skin. It reacts with oxygen in air to form oxides and must be handled in appropriate containment with proper ventilation and personal protective equipment.