Two One-Dimensional Copper-Oxalate Frameworks with the Jahn–Teller Effect: [(CH 3) 3 NH] 2 [Cu(μ-C 2 O 4)(C 2 O 4)]·2.5H 2 O (I) and [(C 2 H 5) 3 NH] 2 [Cu(μ-C 2 O 4)(C 2 O 4)]·H 2 O (II).

Two one-dimensional oxalate-bridged Cu(II) ammonium salts, [(CH₃)₃NH]₂[Cu(μ-C₂O₄)(C₂O₄)]·2.5H₂O (I) and [(C₂H₅)₃NH]₂[Cu(μ-C₂O₄)(C₂O₄)]·H₂O (II) were obtained and characterized. They were composed of ammonium: (CH₃)₃NH⁺ in (I), (C₂H₅)₃NH⁺ in (II), [Cu(μ-C₂O₄)(C₂O₄)²⁻]_n and H₂O. The Jahn–Teller-distorted Cu(II) is octahedrally coordinated by six O atoms from three oxalates and forms a one-dimensional zigzag chain. The hydrogen bonds between ammonium, the anion and H₂O form a three-dimensional network. There is no hydrogen bond between the anion chains. They were insulated at 20 °C with a relative humidity of 40%. Ferromagnetic and weak-ferromagnetic behaviors were observed in I and II, separately. No long-range ordering was observed above 2 K. [ABSTRACT FROM AUTHOR]