A new oxamato-bridged heterotrinuclear NiIICuIINiII complex with irregular spin state structure: Synthesis, spectroscopy, crystal structure and magnetism

A new oxamato-bridged NiIICuIINiII species, [Ni(tacn)(H2O)]2[μ-Cu(pba)](ClO4)2·6H2O 1, (tacn=1,4,7-triazacyclononane; pba=1,3-propylenebis(oxamato)) has been synthesized and structurally as well as magnetically characterized. Complex 1 has a discrete trinuclear NiIICuIINiII structure: Two nickel(II) ions are bridged by [Cu(pba)]2− anion, macrocyclic ligand tacn works as terminal ligand of the nickel(II) center. The magnetic data of compound 1 was analyzed by means ofH̑=−J(S̑Ni1·S̑Cu+S̑Ni2·S̑Cu)+D[S̑z2−1/3S(S+1)]+β[gNi(S̑Ni1+S̑Ni2)+gCuS̑Cu]Hleading to gCu=2.19, gNi=2.18, J=−112.8 cm−1, D=±4.31 cm−1. The parameters are compared with the similar complexes and the irregular spin state structure of complex 1 is also described here.