New macrocyclic polyamines of 3,5-disubstituted 1H-pyrazole. A 13C NMR study of deprotonation and formation of Zn2+ dinuclear complexes

Article abstract of DOI:10.1016/S0040-4039(00)93406-3

Dipodal (2+2) condensation of 3,5-(1H-pyrazole)dicarbaldehyde (3) with 1,5-diamino-3-oxapentane (4) and diethylenetriamine (5) followed by hydrogenation of the resulting Schiff bases (6 and 8), affords two new 26 membered polyaza macrocycles of 1H-pyrazole (7 and 9). The deprotonation of both crowns in basic medium as well as the formation of dinuclear Zn²⁺ complexes (7b and 9b) from the dipyrazolate salts 7a and 9a have been studied by ¹³C NMR.