Magnetic properties of new copper(II) and [copper(II)]₃-manganese(II) complexes of [14]N₄ macrocyclic oxamides

Four new complexes of [14]N₄ macrocyclic oxamides, namely [CuL¹], [CuL²], [(CuL¹)₃Mn](ClO₄)₃ and [(CuL²)₃ Mn](ClO₄)₃ [L¹ and L² are the dianions of 2,3-dioxo-5,6: 3,14-dibenzo-7,12-bis(ethoxycarbonyl)-1,4,8,11-tetraazacyclotetradeca-7,11-diene (H₂L¹) and 2,3-dioxo-5,6:13,14-dibenzo-9-methyl-7,12-bis(ethoxycarbonyl)-1,4,8,11- tetraazacyclo-tetradeca-7,11-diene (H₂L²), respectively], have been prepared and characterized. The observed magnetic susceptibilities of the [(CuL¹)₃Mn] (ClO₄)₃ complex over the ca. 2-300 K range have been fitted to theoretical equations based on the Heisenberg spin Hamiltonian Ĥ = -2JŜ_Mn(Ŝ_Cu1 + Ŝ_Cu2 + Ŝ_Cu3) and molecular field approximation. The results indicated that both the intramolecular and intermolecular magnetic interactions are antiferromagnetic with J_CuMn = -19.8 cm^-1 and zJ′ = -1.41 cm^-1.