[Co(NCS)2(1,2-bis(2-pyridyl)ethylene)]n: A new 1D coordination polymer that shows a metamagnetic transition

Reaction of Co(NCS)2 with 1,2-bis(2-pyridyl)ethylene (2-bpe) leads to four new coordination compounds of composition [Co(NCS)2(CH3OH)4]·2(2-bpe) solvate (1), Co(NCS)2(2-bpe)2(CH3OH)2 (2), Co(NCS)2(2-bpe)2 (3) and Co(NCS)2(2-bpe) (4). The crystal structure of compounds 1 and 2 consists of discrete complexes in which the cobalt(II) cations are octahedral coordinated by two terminal thiocyanato anions and four methanol molecules in 1 and by two terminal N-bonded thiocyanato anions, two 2-bpe ligands and two methanol molecules in 2. In compound 3 also discrete complexes are found but in contrast to 1 and 2 each cobalt(II) cation is tetrahedral coordinated by two terminal N-bonded thiocyanato anions and two 1,2-bis(2-pyridyl)ethylene (2-bpe) ligands. In the most 2-bpe deficient compound 4 the Co cations are also tetrahedral coordinated but the metal cations are linked into chains by the 2-bpe ligands. Magnetic measurements on compound 3 shows only Curie–Weiss paramagnetism whereas for compound 4 a metamagnetic transition is observed at a critical field of HC = 1.9 kOe with antiferromagnetic ordering below and saturated paramagnetism above HC. These results are compared with those for the corresponding compound with 1,2-bis(4-pyridyl)ethylene as ligand.

Graphical abstractFour new coordination compounds based on Co(NCS)2 and 1,2-bis(2-pyridyl)ethylene have been prepared and characterized by single crystal X-ray diffraction. Magnetic measurements reveal that one of these compounds, in which the cations are linked by the N-donor ligand, shows a metamagnetic transition with antiferromagnetic ordering below and saturated paramagnetism above the critical field.Figure optionsDownload full-size imageDownload as PowerPoint slide