The formation of complexes between aza derivatives of crown ethers and primary alkylammonium salts. Part 1. Monoaza derivatives

Abstract

The monoaza derivatives of crown ethers form complexes with primary alkylammonium thiocyanates analogous to those formed by the crown ethers. The n.m.r. spectra of the complexes show temperature dependence which can be analysed in terms of various types of guest exchange processes and conformational changes of the host molecules. In particular, rapid conformational changes of the host macrocycle, accompanied by changes in hydrogen bonding to the guest cation, can occur without dissociation of the complex. The complexes of the monoaza 15-crown-5 analogues involve only a single face of the host macrocycle, and the substituent on the host nitrogen atom and the guest molecule are syn-related in the complex. The monoaza 18-crown-6 analogues form two diastereomeric complexes, having syn- and anti-relationships between the guest molecule and the substituent on the nitrogen atom of the host.