Dynamic Rotational Motions of Vaulted Chiral transtrans ‐Bis(salicylaldiminato)palladium(II) Complexes Bearing Rigid or Flexible Carbon Chain Linkers

摘要

> Planar chiral, trans ‐bis(salicylaldiminato)palladium(II) complexes having a macrocyclic vaulting structure consisting of either a heptamethylene‐butadiynylene‐heptamethylene ( 1 ) or polymethylene ( 2 ) bridge were synthesized and subsequently characterized by NMR, IR, high‐resolution mass spectrometry, and single crystal XRD. The dynamic rotational behaviors of these vaulted complexes resulting from a skipping‐rope‐like molecular motion were examined on the basis of kinetic studies of the racemization of the optically pure (100?% ee ) complexes. The chiral inversion rate was found to be significantly affected by the conformational flexibility of the complexes, which in turn could be controlled by adjusting the linker length, the linker rigidity, and the ligation properties of the solvent.