Evidence for restricted rotation in hydrogen-1 and fluorine-19 nuclear magnetic resonance spectra of cyclopentadienylperfluoroalkylcobalt complexes

Abstract

An extensive series of complexes [(cp)Col(L)R_F][L = phosphorus donor; R_F= CF₃, CF₂CF₃, or CF(CF₃)₂] and [(cp)CoCO(PPh₃)CF₂CF₃]ClO₄(cp =π-cyclopentadienyl), many of them hitherto unreported, have been prepared and characterized. Variable-temperature proton and fluorine n.m.r. spectra of several of the complexes provide evidence for hindered rotation about both metal–carbon and phosphorus–aryl bonds, while the i.r. spectrum of the carbonyl complex suggests the presence of diastereoisomers, the co-ordinated phosphine and the cobalt constituting chiral centres.