Synthesis, crystal structures and magnetic properties of [Co3(NCS)6(admtrz)6]·CH3OH·H2O and [Ni3(NCS)6(admtrz)6]·1.5H2O (admtrz=4-amino-3,5-dimethyl-1,2,4-triazole)

Two linear trinuclear complexes [Co3(NCS)6(admtrz)6]·CH3OH·H2O (1) and [Ni3(NCS)6(admtrz)6]·1.5H2O (2) containing 1,2,4-triazole and NCS anion as bridging ligands have been isolated, and characterized by X-ray diffraction methods. The two complexes are the isostructural neutral linear trimers, in which the central and terminal metal(II) ions are linked by two N1,N2-1,2,4-triazole ligands and one N-bridging NCS anion, while the terminal metal ions complete their octahedral coordination with one monodentate triazole and two N-bonded NCS anions. The magnetic behavior was investigated in the temperature range 5–300 K. The magnetic susceptibility measurements show that the Co(II) ions are weakly antiferromagnetically coupled with J=−2.8 cm−1, while Ni(II) ions are ferromagnetically coupled with J=10.45 cm−1. The nature and the magnitude of the magnetic-exchange of the two complexes have been discussed on the basis of the structural features.