Catalytic hydrophosphination of alkynes using structurally diverse sodium diphenylphosphide donor complexes

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 Ph2P–H with a range of alkynes and prove to be generally effective under ambient conditions, especially when n = 1 in [{Ph2PNa(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.