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

Biradical mononuclear SQ(2) and SQ(2)ZnL(5) complexes, binuclear SQ(2)Zn(L-3)ZnSQ(2) complex, and coordination polymers (SQ(2)ZnL(1(2)))(n) are synthesized by the reactions of bis(3,6-di-tert-butyl-o-benzosemiquinonato)zinc (SQ(2)Zn) with the bidentate N-donor ligands (L1-5) (pyrazine (L-1), 4,4'-dipyridyl (L-2), phenazine (L-3), 4-cyanopyridine (L-4), and pyrimidine (L-5)). The structures of the synthesized compounds are determined by X-ray diffraction analysis (CIF files CCDC nos. 1846558-1846563). The binuclear SQ(2)Zn(L-3)ZnSQ(2) and mononuclear SQ(2)ZnL(5) complexes contain pentacoordinated metal atoms, whereas zinc in the compounds based on the L-1,L-2,L-4 ligands exists in the octahedral environment with the trans-arranged o-semiquinonate ligands. The coordination polymers (SQ(2)ZnL(1(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.