1,2,5-Trimethylpyrrolyl Phosphines: A Class of Strongly Donating Arylphosphines

Abstract

Arylphosphines are among the most important ligands in coordination chemistry and catalysis but are generally inferior to alkylphosphines when strong electron donor properties are required. Herein, we report the synthesis and properties of 1,2,5-trimethylpyrrolyl phosphines and show that their electron-donating ability can exceed that of alkylphosphines. The new phosphines can be prepared on a multi-gram scale in one-pot procedures starting from commercially available reagents. Tris(1,2,5-trimethyl)pyrrolylphosphine P(tmp)3 is a crystalline solid, displays a Tolman electronic parameter (TEP) of 2055.0 cm-1 and can be handled in air. Nickel(0), palladium(II), gold(I), and ruthenium(II) complexes with 1,2,5-trimethylpyrrolyl-based phosphines are reported in addition to preliminary investigations on the use of P(tmp)3 in ruthenium-catalyzed olefin metathesis.