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, Me 3 P─PCN, via the simple reaction of phosphorus tricyanide with trimethylphosphine. This methodology is general for a series of trialkylphosphines, yielding stable adducts R 3 P─PCN (R = Et, n Bu, Cy, t Bu). Comprehensive spectroscopic, structural, and computational studies of adduct Me 3 P─PCN confirm a polarized electron‐sharing P─P bond, with electron density shifted toward the Me 3 P moiety. Enabled by facile P─P bond cleavage, Me 3 P─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.