Coordination properties of macrocyclic nitrogen-containing compounds in anacidic medium

Changes in the stability of macrocyclic 1,4,8,11-tetraazacyclotetradecane [ 14]aneN(4), 1,4,8,12-tetraazacyclopentadecane [15]aneN(4), and bis(N,N-dime thylperhydropyrazine) compounds upon their protonation were studied by the quantum-chemical methods. The symmetric protonated systems are shown to be most stable, and [14]aneN(4) has the highest stability. The behavior of the systems upon stepwise protonation was considered. The effect of macrocycle isomerization in cyclam on the stability of its coordination compounds was studied. The theoretical considerations agree well with the experimental d ata.