Synthesis, Structures And Properties Of Cobalt Thiocyanate Coordination Compounds With 4-(Hydroxymethyl)Pyridine As Co-Ligand

Reaction of Co(NCS)(2) with 4-(hydroxymethyl)pyridine (hmpy) leads to the formation of six new coordination compounds with the composition [Co(NCS)(2)(hmpy))(4)] (1), [Co(NCS)(2)(hmpy)(4)] x H2O (1-H2O), [Co(NCS)(2)(hmpy)(2)(EtOH)(2)] (2), [Co(NCS)(2)(hmpy)(2)(H2O)(2)] (3), [Co(NCS)(2)(hmpy)(2)](n).4 H2O (4) and [Co(NCS)(2)(hmpy)(2)](n) (5). They were characterized by single crystal and powder X-ray diffraction experiments, thermal and elemental analysis, IR and magnetic measurements. Compound 1 and 1-H2O form discrete complexes, in which the Co(II) cations are octahedrally coordinated by two terminal thiocyanato anions and four 4-(hydroxymethyl)pyridine ligands. Discrete complexes were also observed for compounds 2 and 3 where two of the hmpy ligands were substituted by solvent, either water (3) or ethanol (2). In contrast, in compounds 4 and 5, the Co(II) cations are linked into chains by bridging 4-(hydroxymethyl)pyridine ligands. The phase purity was checked with X-ray powder diffraction. Thermogravimetric measurements showed that compound 3 transforms into 5 upon heating, whereas the back transformation occurs upon resolvation. Magnetic measurements did not show any magnetic exchange via the hmpy ligand for compound 5.