Catalytic hydrophosphination of alkynes using structurally diverse sodium diphenylphosphide donor complexes

Abstract

Currently, there is a drive to develop the organoelement chemistry of sodium, the most abundant alkali metal on earth, as an alternative to that of rarer lithium, with the prime focus on sustainability. Organolithium compounds have been essential to the success of synthetic chemistry for more than a century, although their implementation has been essentially confined to stoichiometric synthesis. Here, we report on synthetic, structural, catalytic, mechanistic, and theoretical studies of a series of sodium diphenylphosphides, having unique structures defined by the Lewis base donor D solvating the Lewis acidic sodium cation. These donor complexes are explored as hydrophosphination catalysts on reacting Ph 2 P–H with a range of alkynes and prove to be generally effective under ambient conditions, especially when n = 1 in [{Ph 2 PNa(D) x } n ]. Density functional theory (DFT) studies have shed light on the possible mechanisms of these catalytic cycles and how they relate to the E, Z, or α isomer formed. • Four crystallographically characterized sodium diphenylphosphide donor complexes • Screening of complexes as catalysts in hydrophosphination applications of alkynes • Detailed DFT analysis probing different catalytic mechanisms Homogeneous catalysis relies heavily on the use of precious transition metal catalysts. Here, Whitelaw et al. describe the use of a series of alternative, structurally well-defined compounds based on the earth-abundant metal sodium, which can catalyze hydrophosphination reactions of alkynes leading to alkenes.