Cu^II chain compound showing a ferromagnetic coupling through triple N¹,N²-1,2,4-triazole bridges

[Cu(hyetrz)₃](CF₃SO₃)₂·H₂O [hyetrz = 4-(2′-hydroxyethyl)-1,2,4-triazole] represents the first structurally characterised ferromagnetically coupled Cu^II chain compound containing triple N¹,N²-1,2,4-triazole bridges. catena-[μ-Tris{4-(2′-hydroxyethyl)-1,2,4-triazole-N¹,N²}copper(II)] bis(trifluoromethanesulfonate) hydrate (C₁₄H₂₃F₆S₂O₁₀CuN₉) crystallises in the triclinic space group P_l, a = 13.54(3), b = 14.37(3), c = 15.61(4) Å, α = 95.9(1), β = 104.9(1), γ = 106.5(1)°, V = 2763(11) ų, Z = 4 (Cu^II units). The Cu^II ions are linked by triple N¹,N²-1,2,4-triazole bridges yielding an alternating chain with Cu1−Cu2 = 3.8842(4) Å and Cu2−Cu3 = 3.9354(4) Å. Analysis of the magnetic data according to a high-temperature series expansion gives a J value of +1.45(3) cm⁻¹. The nature and the magnitude of the ferromagnetic exchange have been discussed on the basis of the structural features. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003).