Structure and magnetic properties of a tetranuclear Cu4O4 open-cubane in [Cu(L)]4·4H2O with L2− = (E)-N′-(2-oxy-3-methoxybenzylidene)benzohydrazide

The in-situ formed hydrazone Schiff base ligand (E)-N′-(2-oxy-3-methoxybenzylidene)benzohydrazide (L2−) reacts with copper(II) acetate to a tetranuclear open cubane [Cu(L)]4 complex which crystallizes as two symmetry-independent (Z′ = 2) S4-symmetrical molecules in different twofold special positions with a homodromic water tetramer. The two independent (A and B) open- or pseudo-cubanes with Cu4O4 cores of 4 + 2 class (Ruiz classification) each have three different magnetic exchange pathways leading to an overall antiferromagnetic coupling with J1B = J2B = −17.2 cm−1, J1A = −36.7 cm−1, J2A = −159 cm−1, J3A = J3B = 33.5 cm−1, g = 2.40 and ρ = 0.0687. The magnetic properties have been analysed using the H = −Σi,jJij(SiSj) spin Hamiltonian.