X-ray structure and magnetic properties of a mononuclear complex and a 1D coordination polymer assembled by cobalt(II) ions and a flexible oxamate ligand

This work describes the synthesis, crystal structures and direct current (dc) magnetic properties of two air-stable oxamato-containing cobalt(II) complexes, [Co(H(2)edpba)(dmso)(2)]center dot dmso center dot H2O (1) and [Co(H(2)edpba)(H2O)(2)](n)center dot n(dmso) (2) [H(4)edpba = N,N '-2,2 '-ethylenediphenylenebis(oxamic acid); dmso = dimethylsulfoxide]. 1 is a mononuclear compound, whereas 2 is a neutral chain. Cobalt(II) ions in both compounds are six-coordinate by six oxygen atoms, four of them from two monodeprotonated oxamate groups and the other two from dmso (1)/water (2) molecules in cis (1) and trans (2) positions. Hydrogen bonds between monodeprotonated oxamate fragments of adjacent mononuclear units in 1 lead to a supramolecular chain growing along the crystallographic c axis. Hydrogen bonds involving coordinated water molecules and monodeprotonated oxamate fragments from adjacent chains in 2 result in a supramolecular 2D network. Cryomagnetic measurements reveal the occurrence of magnetically isolated high-spin cobalt(II) ions in agreement with the large values of the shortest intramolecular (1)/intrachain (2) metal center dot center dot center dot metal separation [ca. 10.3 (1) and 10.4 angstrom (2)]. Simultaneous simulation of the chi T-M versus T and M against H data through the Griffith-Figgis Hamiltonian led to the best-fit parameters: lambda = -141.1 (1)/-174.8 cm(-1) (2), sigma = -1.45 (1)/-1.25 (2) and nu = -121.42 (1)/-247.29 cm(-1) (2).