Stereochemie von Metallocenen, 13. Mitt.: Optisch aktive Derivate des Methylcymantrens: Darstellung, Rotationsdispersion und konfigurative Korrelation

Optical Activity from Asymmetric Transition Metal Atoms

“…7), assuming a constant activation energy, gives the rate constants shown in the right-hand side of Table 1 give only upper limits, while the true rate constants are much smaller, it is found that the complex (38) and probably also (40) and (34) have greater configurational stability than the manganese derivative (27b)[861. This means that the complexes (34), (38), and (40), if they were to exist in an optically active form, would racemize more slowly than the manganese complex (27b), which has already been prepared in an optically active form. This is a point that requires experimental verification.…”

“…If signals coalesce with rising-temperature, the rate constants of the reactions involved can be found from the spectra["! If the coalescence temperature is not reached, as in the cases of (34), (38), and (40), it is still possible to give upper limits for the reaction rates, in this case for the change in configuration on the metal atom^[^^,^']. Upper limits found in this way for the rate constants of the ligand exchange are shown in the left-hand side of Table Table 1 …”

“…In the complex C,H,Mo(CO)(NO)P(CH,),C,H, (38), which can be prepared in a reaction analogous to equation (2), the carbonyl and nitrosyl ligands are extremely similar both in their linear structure and in the similar charge distribution. It was therefore interesting to consider whether the differences between the two ligands are sufficient to induce magnetic nonequivalence in the probe P(CH,),C,H,.…”