Trimethylphosphine-Stabilized (Cyano)Phosphinidene: A Versatile PCN Transfer Reagent

The development of phosphorus-containing building blocks is crucial for efficient synthetic protocols in main group element chemistry. Among those, the PCN unit is a key structural motif for the construction of functional molecular frameworks. While anionic PCN-containing species are well-established, the isolation and utilization of neutral PCN molecules remain challenging. Herein, we report a straightforward synthesis of the neutral (cyano)phosphinidene adduct, Me₃P─PCN, via the simple reaction of phosphorus tricyanide with trimethylphosphine. This methodology is general for a series of trialkylphosphines, yielding stable adducts R₃P─PCN (R = Et, ⁿBu, Cy, ^tBu). Comprehensive spectroscopic, structural, and computational studies of adduct Me₃P─PCN confirm a polarized electron-sharing P─P bond, with electron density shifted toward the Me₃P moiety. Enabled by facile P─P bond cleavage, Me₃P─PCN acts as an efficient and versatile PCN transfer reagent, providing access to diverse molecular architectures and opening new avenues for the integration of the PCN unit into complex systems.