Synthesis, crystal structure and magnetic properties of N1,N2-bridged polynuclear Ni(II) complexes

A series of nickel(II) complexes [Ni3(L1)6(H2O)6]Cl6·10H2O (1), [Ni3(L2)6(H2O)6](NO3)5(OH)·2H2O (2) and [Ni2(μ-pz)3(tpm)2](OH)·0.5H2O·C2H5OH (3) were synthesized and structural characterized via X-ray single-crystal diffraction (L1=3,5-dimethanyl-4-amino-1,2,4-triazole, L2=4-2-pyridinyl-1,2,4-triazole, Hpz=pyrazole, tmp=tris(pyrazolyl)methane). 1 and 2 are linear trinuclear cations while 3 has a dinuclear Ni(II) unit, all of which contain bridged triazole or pyrazole ligands with N1,N2-bridged motif. UV–vis spectra of 1–3 show typical octahedral coordination field for Ni(II) ions. The variable-temperature (2–250 K) magnetic measurements reveal the existence of weak anti-ferromagnetic interaction in 1.