Bis-o-Semiquinonate Zinc Complexes with the Bidentate N-Donor Ligands: Synthesis and Magnetic Properties

Abstract

Biradical mononuclear SQ2 $${\text{ZnL}}_{2}^{4}$$ and SQ2ZnL5 complexes, binuclear SQ2Zn(L3)ZnSQ2 complex, and coordination polymers (SQ2ZnL1(2))n are synthesized by the reactions of bis(3,6-di-tert-butyl-o-benzosemiquinonato)zinc (SQ2Zn) with the bidentate N-donor ligands (L1–5) (pyrazine (L1), 4,4'-dipyridyl (L2), phenazine (L3), 4-cyanopyridine (L4), and pyrimidine (L5)). The structures of the synthesized compounds are determined by X-ray diffraction analysis (СIF files CCDC nos. 1846558–1846563). The binuclear SQ2Zn(L3)ZnSQ2 and mononuclear SQ2ZnL5 complexes contain pentacoordinated metal atoms, whereas zinc in the compounds based on the L1,2,4 ligands exists in the octahedral environment with the trans-arranged o-semiquinonate ligands. The coordination polymers (SQ2ZnL1(2))n are capable of depolymerizing on dissolution in organic solvents. According to the data of measuring the temperature dependence of the magnetic susceptibility, the antiferromagnetic exchange between unpaired electrons of the organic radical anions is observed in crystals of the synthesized compounds.