Copper(II) Carboxylates with 2,3,4-Trimethoxybenzoate and 2,4,6-Trimethoxybenzoate: Dinuclear Cu(II) Cluster and µ-Aqua-Bridged Cu(II) Chain Molecule

Copper(II) complexes with 2,3,4-trimethoxybenzoic acid (H234-tmbz) and 2,4,6-trimethoxybenzoic acid (H246-tmbz), [Cu2(234-tmbz)4(H2O)2] (6) and [Cu(246-tmbz)2(µ-H2O)2(H2O)2]n (7), were synthesized and characterized by elemental analysis, infrared and UV-vis spectra and temperature dependence of magnetic susceptibilities (1.9–300 K). The X-ray crystal structures revealed that the former 6 is a dinuclear cluster having syn-syn-bridged Cu2(µ-234-tmbz)4 core with Cu···Cu separation of 2.6009(7) Å, while the latter 7 is a µ-aqua-bridged chain molecule consisting of Cu(246-tmb)2(µ-H2O)2(H2O)2 units with Cu···Cu separation of 4.1420(5) Å. Temperature dependence of magnetic susceptibilities showed that an antiferromagnetic interaction with 2J = −272 cm−1 for 6 and a weak antiferromagnetic interaction with J = −0.21 cm−1 for 7, between the two copper(II) ions. The adsorption isotherm of 6 showed Types I behavior having a 125.4 m2g−1 of specific surface area