ABSTRACT
To evaluate the influence of steric, electronic, and synthetic factors, the synthesis of RuHCl(CO)[P(i)Pr(2)(3,5-(CF(3))(2)C(6)H(3))](2) was carried out, and its Lewis acidity toward Cl- was compared to that of RuHCl(CO)(P(i)Pr(3))(2). In this synthesis, Na(2)CO(3) was shown to be a more effective base than NEt(3), because Na+ can better mask the nucleophilicity of the potential ligand Cl-. An X-ray structure determination of the hydride-free species RuCl(2)(CO)(P(i)Pr(2)Me)(2) shows it to be a dimer, and this solid-state structure persists in solution, but as several different isomers. The synthesis of RuHCl(CO)(P(i)Pr(2)Me)(3) shows that three of this smaller phosphine can crowd around Ru, but dynamic NMR spectra show one phosphine to be weakly bound. The rate of reaction of Me(3)SiC(triple bond)CH with this molecule is suppressed by added free P(i)Pr(2)Me, indicating phosphine dissociation to be a mechanistic component.
ABSTRACT
Palladacycles of the type 2, have been synthesized by treatment of the corresponding chloroalkylcomplexes Pd(CH(2)CMe(2)C(6)H(5))ClL(2) (L(2) = (PMe(3))(2), 2a, or 1,5-cyclooctadiene (cod), 2b) with suitable bases, or by simple ligand exchange reactions from the cyclooctadiene derivative 2b. The metallacycles 2 react with activated alkynes and with sulfur dioxide, giving rise to different insertion products.
ABSTRACT
The sigma-enynyl complex [TpRu(C(Ph)=C(Ph)C identical to CPh)(P-MeiPr2)] efficiently catalyses the regioselective cyclization of alpha,omega-alkynoic acids to yield endocyclic enol lactones having ring size up to 12 atoms.
