Synthesis and Characterization of Cu(II) and Mono-and Dinuclear Pb(II) Complexes Derived from 3,5-Diacetyl-1,2,4-triazole

Template 1:1 condensation of 3,5-diacetyl-1,2,4-triazole with thiocarbohydrazide or car- bohydrazide in the presence of 1 equivalent of Pb(SCN)2 produces mononuclear [2 + 1] com­plexes 1 and 3. The analogous reaction with thiosemicarbazide and semicarbazide produces the dinuclear [1+2] complex 2 and the mononuclear metal free 4. The carbohydrazide deriva­tive 3 reacts with the carbohydrazide or the 1,3-diaminopropane to yield the macrocyclic dinuclear complexes 5 and 6. Direct reaction of 3,5-diacetyl-1,2,4-triazole with thiocarbohydrazide. carbohydrazide, thiosemicarbazide and semicarbazide leads to open [1+1] ligands L1, L2, L3, L4, and closed [1+1] ligands (mesocyclic ligands) L5 and L6 were prepared by addition of 1 equivalent of LiOH to the reaction mixture. The reaction of open and mesocyclic [1+1] ligands with copper(II) salts gives [CuLX2] and [Cu2+L2-] complexes. All these compounds have been characterized by 1H NMR, IR, electronic and mass spectra and by analytical data.