The reaction of [Li(Et2O)2][Cp′2MCl2] (Cp′ = C5Me5; M = Nd, Sm) with 1 equivalent of Li(CH2)(CH2)PRR′(a, R = Me, R′ = Ph; b, R = R′= Ph; c, R = R′= Me; d, R = R′ = t-Bu) produces Cp′2M[(CH2)(CH2)PPR′]·(LiCl)2 (I, M = Sm; II, M = Nd) in moderate yield. Variable-temperature 1H NMR studies on Cp′2M[(CH2)(CH2)P(Me)R]·(LiCl)2 (M = Nd, Sm; R = Me, Ph) show that the methyl protons on the phosphorus of the chelating ylide undergo rapid exchange with the bridging methylene protons even at -40°C. A mechanism which is based on a series of metal-carbon bond breaking, rotation and recombination processes has been proposed for the fluxional behaviour. The ylidic complexes react with hydrogen (1 atm) at ambient temperature producing C5Me5H and the corresponding phosphonium salts, [RR′PMe2]Cl. 1H NMR studies on the reactivity of Ia towards hydrogen and acid review that the metal-carbon bond formed between the lanthanide metal and the chelating phosphorus ylide is more stable than that formed between the lanthanide metal and the pentamethylcyclopentadienyl ring.
Scopus Subject Areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry
- Materials Chemistry