Metal-Organic Frameworks of Cobalt(II) with 4,7-Di(1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole and Aromatic Dicarboxylic Acids: Synthesis, Crystal Structures, and Magnetic Properties

Abstract

The reactions of cobalt(II) nitrate with 4,7-di(1,2,4-triazol-1-yl)-2,1,3-benzothiadiazole (Tr2btd) and aromatic dicarboxylic acids (terephthalic (H2bdc), 2,6-naphthalenedicarboxylic (2,6-H2Ndc), and 2,5-furandicarboxylic (2,5-H2Fdc) acids) afford metal-organic frameworks [Co(Tr2btd)(bdc)]n (I) and {[Co2(Tr2btd)(Dmf)(2,6-Ndc)2]·Dmf}n (II) with the layered structures and chain metal-organic framework [Co(Tr2btd)2(H2O)(2,5-Fdc)]n (III). Compounds I and III are paramagnetic in a temperature range of 1.77–300 K without exchange interactions between the Co2+ cations, and compound II exhibits the antiferromagnetic interaction between the Co2+ cations in the binuclear building blocks with the exchange interaction constant J ≈ −100 K. Single crystals of the phase of compound IIIa with the identical composition but different structure are found when taking samples for X-ray diffraction (XRD) analysis. The molecular structures of metal-organic frameworks I, II, III, and IIIa are determined by XRD (CIF files CCDC nos. 2343141 (I), 2343297 (II), 2343296 (III), and 2343140 (IIIa)).