tBu3P

tBu3P, also known as tri-tert-butylphosphine, is an organophosphorus compound with the chemical formula P(C(CH3)3)3. It is a tertiary phosphine and is characterized by its bulky tert-butyl groups attached to the phosphorus atom. This steric bulk significantly influences its chemical properties and reactivity.

Tri-tert-butylphosphine is a white, crystalline solid at room temperature and is air-sensitive, often requiring handling under an inert atmosphere to prevent oxidation. It is soluble in many organic solvents. The large steric hindrance around the phosphorus atom makes tBu3P a highly effective ligand in organometallic chemistry. Its bulkiness can promote reductive elimination and destabilize low-coordinate metal complexes, which are often highly reactive intermediates.

In catalysis, tBu3P is widely employed as a ligand, particularly in palladium-catalyzed cross-coupling reactions such as Suzuki, Heck, and Buchwald-Hartwig amination. Its electronic properties, being an electron-rich phosphine, also contribute to its effectiveness in these catalytic systems, often leading to higher reaction rates and improved yields compared to less bulky or less electron-donating phosphine ligands. The steric bulk can also influence the regioselectivity and stereoselectivity of catalyzed reactions. Due to its air sensitivity, it is often handled as a solution or its more stable hydrochloride salt, which can be deprotonated in situ.