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

An extensive series of complexes [(cp)Col(L)RF][L = phosphorus donor; RF= 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...