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 (H 2 L) with copper(II), nickel(II), and cobalt(II) salts afford a series of unusual structures; among them are the homoleptic binuclear complexes [Ni 2 (H 2 L) 2 (H 2 O) 4 ](NO 3 ) 4 · 6H 2 O ( 1 ) and [Ni 2 (H 2 L) 2 Cl 2 ]Cl 2 · 4H 2 O · 2C 4 H 8 O 2 ( 2 ), the octanuclear complex [Ni 8 (H 2 L) 12 ](NO 3 ) 16 · 21H 2 O ( 3 ), and the tetranuclear complexes [Cu 4 (HL) 4 ](ClO 4 ) 4 · C 2 H 5 OH · 3H 2 O ( 4 ), [Co 4 (HL) 2 (H 2 L) 2 (H 2 O) 4 ](NO 3 ) 8 · C 2 H 5 OH · 6H 2 O ( 5 ), and [Co 4 (HL) 2 (H 2 L) 2 (H 2 O) 4 ] · (ClO 4 ) 8 · 8H 2 O ( 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 ).