Syntheses, Crystal Structures, and Properties of Two Novel Trinuclear Copper Complexes Constructed by a Tripodal Heptadentate Ligand Containing Three Imidazolate Groups

Two Cu-II complexes, {Cu-3[(mim)(3)htren](2)}(ClO4)(6)center dot 2H(2)O (1) and {Cu-3[(mim)(3)htren](2)} (PF6)(6)center dot 2(CH3CN)center dot 2H(2)O (2) with the tripodal heptadentate ligand (mim)(3)htren (= tris{2-[2-(1-methyl)imidazolyl]methylaminoethyl}amine) were synthesized and characterized. In complex 1 and 2, the tripodal ligand (mim)(3)htren coordinates in a very unusual configuration to the copper atoms, which resulted in trinuclear complexes. In the trinuclear cation, {Cu-3[(mim)(3)htren](2)}(6+), the middle atom located on a crystallographic inversion center is coordinated in an elongated octahedral arrangement for 1 and coordinated in square-planar arrangement for 2, respectively, and the other two Cu-II atoms are coordinated in a distorted square-pyramid. The results from magnetic data, measured in the temperature range 2.0-300 K, showed that 1 and 2 obeyed the Curie-Weiss law with Weiss constants theta = 0. 10 and 0.14 K, respectively, and the same Curie constant C = 1.14 K.mol(-1), indicating weak ferromagnetic interactions in the two trinuclear entities.