A Ruthenophosphanorcaradiene as a Synthon for an Ambiphilic Metallophosphinidene.

Reaction of the ruthenium carbene complex Cp*(IPr)RuCl ( 1 ) (IPr = 1,3-bis(Dipp)imidazol-2-ylidene; Dipp = 2,6-diisopropylphenyl) with sodium phosphaethynolate (NaOCP) led to intramolecular dearomatization of one of the Dipp substituents on the Ru-bound carbene to afford a Ru-bound phosphanorcaradiene, 2 . Computations by DFT reveal a transition state characterized by a concerted process whereby CO migrates to the Ru center as the P atom adds to the π system of the aryl group. The phosphanorcaradiene possesses ambiphilic properties and reacts with both nucleophilic and electrophilic substrates, resulting in rearomatization of the ligand aryl group with net P atom transfer to give several unusual metal-bound, P-containing main-group moieties. These new complexes include a metallo-1-phospha-3-azaallene (Ru─P═C═NR), a metalloiminophosphanide (Ru─P═N─R), and a metallophosphaformazan (Ru─P(═N─N═CPh 2 ) 2 ). Reaction of 2 with the carbene 2,3,4,5-tetramethylimidazol-2-ylidene (IMe 4 ) produced the corresponding phosphaalkene DippP═IMe 4 .