Cobalt(III) Bis-o-semiquinone Complexes with 1-Aryl-3,5-Diphenylformazan Ligands: Synthesis, Structures, and Magnetic Properties

New heteroligand cobalt(III) bis-3,6-di-tert-butyl-o-benzosemiquinone complexes with 1-(p-X-phenyl)-3,5-diphenylformazan ligands Co(3,6-SQ)2LX (Х is fluorine (I), chlorine (II), bromine (III), iodine (IV), and methyl (V)) are synthesized. The molecular structures of compounds I, II, and IV are determined by X-ray structure analysis (CIF files CCDC nos. 2060727 (I), 2052592 (II), and 2060728 (IV)). The coordination environment of the central cobalt ion in the studied complexes is a weakly distorted octahedron, and the degree of distortion insignificantly changes depending on the substituent. According to the X-ray structure data and results of magnetic and spectral studies, compounds I–V are low-spin complexes of cobalt(III) bound to two radical anion o-semiquinone ligands and one formazan anion. The magnetic behavior of complexes I–V in a temperature range of 50–300 K is characterized by the predomination of intramolecular exchange interactions of the antiferromagnetic type, whereas in the range lower than 50 K complexes II–V exhibit ferromagnetic ordering caused by intermolecular exchange interactions between the paramagnetic ligands.