Three macrocyclic Lewis acidic hosts containing two symmetrically disposed dichlorostanna moieties (1-3; ring sizes, 18, 22, and 26 atoms, respectively) have been prepared as has an acyclic ditin model, 5, 5, 16, 16-tetrachloro-5, 16-distannaeicosane (4). The complexation of 1-4 and dibutyltin dichloride (5) with chloride ion in acetonitrile was studied by ll9Sn NMR spectroscopy. Rapid exchange of chloride between tin atoms occurred at all ratios of ...
