NMR-STUDIES ON THE LI-14-CROWN-4 LARIAT ETHERS( AND NA+ COMPLEXES OF DIBENZO)

The Li+ and Na+ complexes of a series of substituted dibenzo-14-crown- 4 ethers bearing alkyl, ether, hydroxylic and carboxylic functional gr oups have been investigated in solution by H-1 and C-13 NMR spectrosco py. As was found previously for the uncomplexed ligands, the orientati on of the sidearm relative to the crown cavity in the complexes depend s on the nature of the atom linking the sidearm to the macrocyclic rin g. Most significantly, when the sidearm is attached to the macrocyclic ring through an ether linkage the sidearm is oriented towards the cav ity, resulting in intramolecular interactions between the bound carbon and secondary donor groups on the sidearm, which appear to be stronge r for sodium than for lithium.