Copper(II), Nickel(II), and Cobalt(II)/(III) Self‐Assembled Polynuclear Complexes of Bis[(pyridin‐2‐yl)‐1,2,4‐triazol‐3‐yl]]methane

• Published in: European journal of inorganic chemistry 2017-01, Vol.2017 (3), p.704-712
• Main Authors: Gusev, Alexey N., Shul'gin, Victor F., Ryush, Irina O., Hasegawa, Miki, Kiskin, Mikhail A., Efimov, Nikolay N., Lyssenko, Konstantin A., Eremenko, Igor L., Linert, Wolfgang
• Format: Article
• Language: English
• Subjects: Antiferromagnetism; Cations; Copper; Coupling (molecular); Exchange; Ferromagnetism; Ligands; Magnetic properties; Polynuclear complexes; Self assembly; Triazole ligands
• ISSN: 1434-1948; 1099-0682
• DOI: 10.1002/ejic.201601107

The reactions of bis[(pyridin‐2‐yl)‐1,2,4‐triazol‐3‐yl]methane (H2L) with copper(II), nickel(II), and cobalt(II) salts afford a series of unusual structures; among them are the homoleptic binuclear complexes [Ni2(H2L)2(H2O)4](NO3)4·6H2O (1) and [Ni2(H2L)2Cl2]Cl2·4H2O·2C4H8O2 (2), the octanuclear complex [Ni8(H2L)12](NO3)16·21H2O (3), and the tetranuclear complexes [Cu4(HL)4](ClO4)4·C2H5OH·3H2O (4), [Co4(HL)2(H2L)2(H2O)4](NO3)8·C2H5OH·6H2O (5), and [Co4(HL)2(H2L)2(H2O)4]·(ClO4)8·8H2O (6). All these compounds have been characterized by different techniques, such as elemental analysis, electrospray mass spectrometry (ES‐MS), UV/Vis spectroscopy, X‐ray structural analyses, and magnetic measurements. It was found that the nature of the cation and the metal/ligand ratio have a substantial impact on the coordination geometries of the unique complexes. The magnetic properties of compounds 1 and 2 show the presence of intramolecular ferromagnetic exchange interactions (J = +2.3 and +15.2 cm–1) combined with intermolecular antiferromagnetic coupling. Complexes 3, 5, and 6 show weak intramolecular antiferromagnetic interactions, while complex 4 shows quite strong antiferromagnetic behavior (J = –53.7 cm–1). The structure and properties of polynuclear complexes based on the self‐assembly of bis[(pyridin‐2‐yl)‐1,2,4‐triazol‐3‐yl]methane with CuII, NiII, and CoII cations are studied.