Synthesis of Water-Soluble, Aliphatic Phosphines and Their Application to Well-Defined Ruthenium Olefin Metathesis Catalysts

Water-soluble aliphatic phosphines Cy_2P(CH_2)_2N(CH_3)_3^+Cl^- (14), Cy_2P[4-(N,N-dimethylpiperidinium)]^+Cl^- (15), Cy_2P(CH_2)_2SO_3^-Na^+ (16), and CyP[(CH_2)_2N(CH_3)_3^+Cl^-]_2 (17) (Cy = cyclohexyl) were prepared from air-stable, borane-protected precursors. Spectroscopic investigations of corresponding Pd(PR_3)_2Cl_2 complexes were used to estimate the steric parameters of these new phosphines. Spectroscopic investigation of Ni(CO)_3PR_3 complexes of the new phosphines indicated that phosphines bearing quaternary amine functionalities were less electron donating than tricyclohexylphosphine, while the presence of a sulfonate group increased phosphine electron donation. Cationic phosphines 14 and 15 were used to synthesize water-soluble ruthenium carbene complexes of the type (Cy_2PR)_2Cl_2RuCHPh. These complexes initiate the ring-opening metathesis polymerization (ROMP) of functionalized 7-oxanorbornenes in water, methanol, and aqueous emulsions