Optisch aktive übergangsmetall-komplexe: LXXXV. Darstellung, eigenschaften und konformationsanalyse von optisch aktiven CpCo-Komplexen☆

Abstract The Schiff bases from 2-pyridine-carbaldehyde, 2-acetylpyridine, 2-benzoylpyridine, 2-pyrrole-carbaldehyde, and 2-acetylpyrrole with (−)-1-phenylethylamine and (−)-3-aminomethylpinane were synthesized. The pyridine Schiff bases αγ were used as neutral compounds and the pyrrole Schiff bases δHζH were used as anions δζ in the reaction with CpCo(CO)I 2 and CpCo(CO)(C 3 F 7 )I. In place of the covalently bonded iodine ligand different monodentate ligands bp were incorporated. Compounds of the type CpCo(αζ)(ap) and [CpCo(αζ)(ap)]X with X = I, PF 6 are formed. All the complexes consist of pairs of diastereomers differing only in the Co configuration. The diastereomers exhibit different 1 H NMR spectra. The Co configuration in all the compounds is labile except the C 3 F 7 derivatives. A conformational analysis establishes which of the diastereomers is the thermodynamically more stable one, on the basis of the following arguments and methods: NOE-difference spectroscopy, diastereomer ratios at equilibrium, chemical shifts of the Cp signals, and CD spectra.