Ferromagnetic Coupling by Orthogonal Magnetic Orbitals in a Heterodinuclear Cu^IIV^IVO Complex and in a Homodinuclear Cu^IICu^II Complex

The heterodinuclear complex [LCu^IIV^IVO] 1 was synthesized by using a new unsymmetric dinucleating ligand based on 1,8-naphthalenediol, whereas the homodinuclear Cu^IICu^II complex 2 has a bridging β-diketimineamid unit. Here we report on the synthesis, molecular structures, and magnetic properties of 1 and 2. In the solid state, both complexes dimerize to tetranuclear entities 1₂ and 2₂. The intradimer interaction in both complexes is ferromagnetic because of the orthogonality of the magnetic orbitals (J₁₂ = +45.6 cm^-1 in 1 and +4.8 cm^-1 in 2). The interdimer interaction in 1 is also ferromagnetic, giving a S_t = 2 ground state.