A Rutheno-Phosphanorcaradiene as a Masked Ambiphilic Metallo-Phosphinidene

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. 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 -system of the aryl group. The phosphanorcaradiene possesses ambiphilic properties and reacts with both nucleophilic and electrophilic substrates, resulting in re-aromatization 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 metallo-iminophosphanide (Ru-P=N-R), and a metallo-phosphaformazan (Ru-P(=N-N=CPh2)2). Reaction of 1 with the carbene 2,3,4,5-tetramethylimidazol-2-ylidene (IMe4) produced the corresponding phosphaalkene DippP=IMe4.