ISSN 1070-3284, Russian Journal of Coordination Chemistry, 2007, Vol. 33, No. 1, pp. 37–44. © Pleiades Publishing, Ltd., 2007. Original Russian Text © E.V. Lider, V.N. Elokhina, L.G. Lavrenova, Yu.G. Shvedenkov, L.A. Sheludyakova, E.V. Peresypkina, 2007, published in Koordinatsionnaya Khimiya, 2007, Vol. 33, No. 1, pp. 39–46. 37 The synthesis and study of 3d-metal complexes with 1,2,4-triazoles are among promising directions of coor- dination chemistry [1]. Since 1,2,4-triazole and its derivatives, which do not contain substituents in posi- tions 1 and 2 of triazole ring, most frequently exhibit bidentate-bridging coordination through the N(1) and N(2) atoms, they can be used to synthesize bi-, tri-, and polynuclear complexes of transition metals. Antiferro- and ferromagnetic exchange interactions between para- magnetic ions are observed in the Co(II), Ni(II), and Cu(II) complexes with these ligands [1–5]. Complexes of different Fe(II) salts with 1,2,4-triazole and its 4-substituted derivatives show spin transition 1 Ä 1 5 í 2 , which is attended by thermochromism (pink white color transition) [6–9]. Due to the presence of a bulky substituent in posi- tion 4 of a triazole ring, trinuclear linear complexes are formed most frequently, rather than polynuclear com- plexes [4, 5, 9–11]. Three types of trinuclear com- pounds of 3d metals with 1,2,4-triazole derivatives are known, namely, A, B, and C: N N N M M O NN N O N N N O N N N M O N N N O N N N O N N N M M O NN N O N N N N N N N M O N N N O N N N N N N N N (Ä) (B) Complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-Dichlorophenyl)-1,2,4-Triazole E. V. Lider a , V. N. Elokhina b , L. G. Lavrenova a , Yu. G. Shvedenkov a , L. A. Sheludyakova a , and E. V. Peresypkina a a Institute of Inorganic Chemistry, Siberian Division, Russian Academy of Sciences, pr. Akademika Lavrent’eva 3, Novosibirsk, 630090 Russia b Favorsky Institute of Chemistry, Siberian Division, Russian Academy of Sciences, Irkutsk, Russia Received January 12, 2006 Abstract—Novel oligonuclear complexes of Co(II), Ni(II), and Cu(II) with 4-(3,4-dichlorophenyl)-1,2,4-tria- zole (L) of the composition [M 3 L 10 (H 2 O) 2 ](NO 3 ) 6 (M = Co(II), Ni(II)), [Ni 3 L 6 (H 2 O) 6 ]Hal 6 (Hal = Cl – , Br – ), and [Cu 5 L 16 (H 2 O) 2 ](NO 3 ) 10 · 2H 2 O were synthesized and studied by magnetic susceptibility, electronic and IR spectroscopy, and powder X-ray diffraction methods. All the above complexes are X-ray amorphous. Antifer- romagnetic exchange interactions between the M 2+ ions were discovered in the [Co 3 L 10 (H 2 O) 2 ](NO 3 ) 6 and [Ni 3 L 10 (H 2 O) 2 ](NO 3 ) 6 complexes, whereas ferromagnetic exchange interactions were observed in the com- plexes [Ni 3 L 6 (H 2 O) 6 ]Cl 6 , [Ni 3 L 6 (H 2 O) 6 ]Br 6 , and [Cu 5 L 16 (H 2 O) 2 ](NO 3 ) 10 · 2H 2 O. DOI: 10.1134/S107032840701006X