Substitution reactions of diphenyl-2-pyridylphosphine with [(η5-C5Me5)M(μ-Cl)Cl]2 (M = Rh or Ir) dimers: Isolation of mono–, di– and chelating complexes

Aspects of Phosphaallene Chemistry: Heat-Induced Formation of 1,2-Dihydrophosphetes by Intramolecular Nucleophilic Aromatic Substitution and Photochemical Generation of Tricyclic Phosphiranes

3H-Phosphaallenes are accessible on a new and facile route and show a fascinating chemical behavior. The thermally induced rearrangement of Mes*P═C═C(H)R' (R' = tBu, Ad) afforded by C-H activation, isobutene elimination, and C-C and P-H bond formation bicyclic 1-benzo-dihydrophosphetes (2) with PC₃ heterocycles. DFT calculations suggest a mechanism with intramolecular nucleophilic aromatic substitution and replacement of an alkyl group by the nucleophilic α-C atom of the phosphaallene. These bicycles formed W(CO)₅ complexes (3) or afforded 1,2-dihydrophosphetes with P-bound alkenyl groups by catalyst-free hydrophosphination of alkynes (4 and 5). The resulting bulky phosphines formed complexes with IrCp*Cl₂, RuCl₂, AuCl, or CuO₃SCF₃. The Ru atom is coordinated by the P atom and a phenyl group. Irradiation of TripP═C═C(H)tBu led by the insertion of the central C atom of the P═C═C group into the α-C-H bond of an iPr substituent and by C-C and P-C bond formation to a new isomer of phosphaallenes, 10, which features a strained PC₂ heterocycle. It formed adducts with M(CO)₅ (M = Cr, Mo, W) and AuCl and reacted with SO₂Cl₂ by cleavage of one of the phosphirane P-C bonds to yield PC₄ or PC₅ heterocycles. Hydrolysis yielded a PC₅ compound with a P(O)Cl group.

Iminophosphanes: Synthesis, Rhodium Complexes, and Ruthenium(II)-Catalyzed Hydration of Nitriles

Highly stable iminophosphanes, obtained from alkylating nitriles and reaction of the resulting nitrilium ions with secondary phosphanes, were explored as tunable P-monodentate and 1,3-P,N bidentate ligands in rhodium complexes. X-ray crystal structures are reported for both κ¹ and κ² complexes with the counterion in one of them being an unusual anionic coordination polymer of silver triflate. The iminophosphane-based ruthenium(II)-catalyzed hydration of benzonitrile in 1,2-dimethoxyethane (180 °C, 3 h) and water (100 °C, 24 h) and under solvent free conditions (180 °C, 3 h) results in all cases in the selective formation of benzamide with yields of up to 96%, thereby outperforming by far the reactions in which the common 2-pyridyldiphenylphosphane is used as the 1,3-P,N ligand.