Bi- and trinuclear cobalt based coordination polymers constructed from aromatic polycarboxylic acids and 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene: Crystal structure and magnetic properties

Abstract

Two new metal–organic frameworks (MOFs) [Co(btx)(bdc)(H 2O)] n 1 and [Co 3(btx) 3(btc) 2(H 2O) 2] n 2, (btx = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene; H 2bdc = 1,4-terephthalate acid; H 3btc = 1,3,5-benzenetricarboxylate acid) have been synthesized and characterized by single-crystal X-ray diffraction studies and low temperature magnetic measurements. Compounds 1 and 2 are three-dimensional compounds whose structures can be described as layers of Co 2 units ( 1) and Co 3 ( 2) units with the carboxylate groups acting as mono or bidentate ligand, which are further connected through the flexible bis(triazole) ligand. The study of the magnetic properties of 1 and 2 in the temperature range 2–300 K shows the occurrence of weak ferromagnetic interactions in 1 due to the anti– syn carboxylate bridge and weak antiferromagnetic interactions in 2 between the high-spin Co(II) ions.