Metallosupramolecular compounds based on Cu(ii)/oxalate/twisted NSSN ligands showing a new in situ S–C bond cleavage

Abstract

Four new complexes, [Cu₂(C₂O₄)₂(SCS)]·3H₂O (1), [Cu₂(C₂O₄)₃(SCSH)₂]·H₂O (2), [Cu(C₂O₄)(SS)₂]·3H₂O (3) and [Cu(C₂O₄)(SS)]·6H₂O (4) [where SCS = bis(4-pyridylthio)methane and SS = 4,4′-dipyridyldisulfide], have been synthesized by the reaction of the SS and SCS ligands with the corresponding copper(II) oxalate salt. The different synthetic conditions allowed control of the preparation of a 3D open metal–organic framework in 1, a dinuclear zwitterionic molecular compound in 2 and one- and two-dimensional (1D and 2D) coordination polymers in 3 and 4, respectively. Compound 4 was also obtained by in situ transformation of the dithioether ligand (SCS) to the disulfide ligand (SS) under hydrothermal conditions at 150 °C. The topology of the structures has been studied and 1 is a new 3D MOF with a binodal 4-connected node in a scarcely known network topology. Different numbers and topologies of water molecules are hosted in the crystal lattices of the compounds. The integrity of the frameworks after dehydration has been validated and discussed. The magnetic properties of compounds 1, 2 and 4 have also been investigated. Strong antiferromagnetic behaviour was found in 1 and weak antiferromagnetic coupling was observed in 2 and 4. The magneto-structural correlations that govern these interactions are discussed in detail.