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

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).