Orbital levels of crown ethers and related macrocycles studied by ultraviolet photoelectron spectroscopy; relationship to complexation studies

Abstract

Ultraviolet photoelectron spectroscopy has been used to measure the valence-shell ionization potentials of several crown ethers and other macrocyclic ligands. A comparison is made with results for corresponding open-chain and other model compounds. In general, evidence is found for appreciable through-bond or through-space interactions among the heteroatom lone-pair orbitals in the macrocyclic molecules, making these molecules softer ligands than would otherwise be anticipated.