Ferromagnetic and mixed-valence copper coordination polymers assembled by polycarboxylates and 2,6-bis(1,2,4-triazolyl)pyridine

Hydrothermal reactions of Cu(NO3)2 with 2,6-bis(1,2,4-triazolyl)pyridine (btp) and 1,3,5-benzenetricarboxylic acid (H3btc) or 1,2,4,5-benzenetetracarboxylic acid (H4btec) in base aqueous solution afford two novel complexes [Cu2(btp)(btc)(H2O)(OH)]n (1) and [Cu2(btp)(Hbtec)]n · nH2O (2). Complex 1 is a coordination polymer where a carboxylate and a hydroxyl are bound to Cu(II) ions to form (μ-OH)(μ-O2CR)Cu2 core, which is ferromagnetic couple with 2 J = 21.30 cm−1. Complex 2 is a 3-D coordination polymer. Bond valence sum (BVS) analysis indicates it is a mixed-valence compound. Cu(I) is three-coordinated by triazole N-donors, while Cu(II) is four-coordinated by a triazole N and three carboxyl O-donors. Both complexes are quite thermal stable.