Abstract

The hydrothermal synthesis, characterization, single crystal X-ray structures and magnetic properties of three-dimensional coordination polymers, [M₃(CTC)₂(μ-H₂O)₂(H₂O)₂]·5(H₂O) (1: M = Co, 2: M = Ni), employing the flexible cis,cis-cyclohexane-1,3,5-tricarboxylate (CTC or C₉H₉O₆³⁻) are described. X-Ray crystal structure analyses reveal that 1 and 2 are isostructural. They belong to the triclinic system, P: a = 7.799(2), b = 9.212(1), c = 10.784(2) Å, α = 107.595(3), β = 92.877(3), γ = 110.248(3)°, V = 682.4(2) Å³ and Z = 2 for 1, and a = 7.694(1), b = 9.210(1), c = 10.764(2) Å, α = 108.598(3), β = 92.300(3), γ = 109.814(3)°, V = 670.6(2) Å³ and Z = 2 for 2. They consist of trinuclear motifs of pseudo-octahedral MO₆ linked through μ-OH₂ and μ-carboxylate to generate one-dimensional chains, which are further bridged by the tricarboxylate to form a non-interpenetrated three-dimensional network. The network possesses extended channels along all three crystallographic axes in which water molecules reside. Each carboxylate group displays a different coordination mode to the metals. The temperature dependence of the magnetic susceptibilities indicates dominant antiferromagnetic interaction within the trimer of the cobalt complex, tending towards a ferrimagnetic alignment at low temperatures, and mostly ferromagnetic interactions for the nickel complex.