Ferromagnetic Copper(II) Complex Containing Ferrocenecarboxylato Bridging Ligands

The synthesis and characterization of the copper(II) complex [Cu2(dpt)2{(μ-O2C)[(η5-C5H4)Fe(η5-C5H5)]}2](ClO4)2 (1), where dpt = dipropylenetriamine, are reported, and its structure was determined by single-crystal X-ray analysis. The compound crystallizes in the monoclinic system, space group P21/n, with a = 9.920(2) Å, b = 12.925(2) Å, c = 15.768(3) Å, β = 93.17(1)°, and Z = 2. The cationic part of 1 shows a tetrametallic core in which two ferrocenecarboxylato groups act as (O,O‘) bridging ligands between two copper(II) ions with a square-pyramidal environment. Susceptibility measurements on this compound indicate a ferromagnetic, albeit weak, coupling between the two paramagnetic centers, with best-fit values of J = +2.5(3) cm-1 and giso = 2.12(1). Magnetostructural correlations can be qualitatively explained on the basis of the topology of their chairlike core. A quantitative investigation has been performed by means of ab initio density functional theory based calculations in the broken-symmetry approach.