The reactions of pyrimidine 2 carbonitrile and 4,6 dimethylpyrimidine 2 carbonitrile with hydrazine hydrate were investigated. Intermediates in the route of successive transformations of pyrimidine 2 carbonitrile (pyrimidine 2 carbamidrazone and 1,2 bis[amino(pyrimidin 2 yl)methylidene]hydrazine) into trinuclear heterocyclic compounds, viz., symmetrical di(pyrimidin 2 yl) 1,4 dihydro 1,2,4,5 tetrazines and di(pyrimidin 2 yl) 4H 1,2,4 triazol 4 amines (potential polydentate ligands), were isolated. The oxidative dehydrogenation of di(pyrimidin 2 yl) 1,4 dihydro 1,2,4,5 tetrazines afforded the corresponding 3,6 di(pyrimidin 2 yl) 1,2,4,5 tetrazines.Key words: pyrimidine 2 carbonitrile, 4,6 dimethylpyrimidine 2 carbonitrile, pyrimidine 2 carbamidrazone, 3,6 di(pyrimidin 2 yl) 1,4 dihydro 1,2,4,5 tetrazines, 3,6 di(pyrimidin 2 yl) 1,2,4,5 tetrazines, 3,5 di(pyrimidin 2 yl) 1H 1,2,4 triazole, 3,5 di(pyrimidin 2 yl) 4H 1,2,4 triazol 4 amines. Substituted 1H and 4H 1,2,4 triazoles exhibit prop erties of metal corrosion inhibitors. 1 These compounds are used also as ligands for the synthesis of transition metal complexes, being coordinated to metal ions through the N(1),N(2) or N(2),N(4) atoms of the triazole ring to form oligo or polynuclear complexes. 2 Transition metal com plexes with triazoles can exhibit ferro or antiferromag netic exchange interactions. 3,4 For the Fe II complexes, the spin transition 1 A 1 ⇔ 5 T 2 and the thermochromism can be observed. 5-7 4H 1,2,4 Triazol 4 amines, unlike par ent 1H 1,2,4 triazole, are usually coordinated to metal atoms as bidentate bridging ligands through the N(1) and N(2) atoms of the triazole ring. 2
