Base‐Stabilized Phosphinidene Oxide, Imide and Sulfide.

Oxidation of a base‐stabilized phosphinidene (κ2‐NNP)P (12, NNP=phosphinoamidinate) with N2O afforded a labile phosphinidene oxide (κ2‐NNP)P=O (16) which was characterized by NMR spectroscopy. Further oxidation of 16 by N2O or reaction of 12 with two equivalents of pyridine oxide afforded the isolable dioxide (κ2‐NNP)PO2 which was characterized by NMR and SC XRD. Trapping of 16 with tolyl isocyanate resulted in P=O/N=C metathesis, eventually affording a urea‐ligated phosphine (κ1‐NNP)P(NTol)2C=O (17) The mechanism of this reaction was elucidated by DFT calculations. Reactions of phosphinidene 12 with azides generated transient imines (NNP)P=NR, which in the case of R=Tol underwent cycloaddition with tolyl Isocyanate to afford the urea product 17, and in the case of R=SiMe3 reacts with N3SiMe3 via the addition of N−Si across the P=N bond affording, after the extrusion of dinitrogen, a P,N‐heterocyclic compound. Both products of the reactions with azides have been fully characterized, both in solution and the solid‐state. Finally, reaction of phosphinidene 12 with one equivalent of sulfur resulted in the isolation of the base‐stabilized phosphinidene sulfide (κ2‐NNP)P=S that has also been fully characterized. [ABSTRACT FROM AUTHOR]