Heteronuclear Complexes of Macrocyclic Oxamide with Co-ligands:  Syntheses, Crystal Structures, and Magnetic Properties

Four heteronuclear complexes Mn(CuL)<sub>2</sub>(SCN)<sub>2</sub> (<b>1</b>), {[Mn(CuL)<sub>2</sub>(μ-dca)<sub>2</sub>]·2H<sub>2</sub>O}<i><sub>n</sub></i> (<b>2</b>), Zn(CuL)<sub>2</sub>(SCN)<sub>2</sub> (<b>3</b>), and [Fe(CuL)(N<sub>3</sub>)<sub>2</sub>]<sub>2</sub> (<b>4</b>) incorporating macrocyclic oxamide ligands have been synthesized and structurally characterized. L is the dianion of diethyl 5,6,7,8,15,16-hexahydro-6,7-dioxodibenzo[1,4,8,11]-tetraazacyclotetradecine-13,18-dicarboxylate, and dca is the dicyanamide. The structure of <b>1</b> or <b>3</b> consists of oxamido-bridged trinuclear [M<sup>II</sup>Cu<sup>II</sup><sub>2</sub>] molecules (for <b>1</b>, M is the manganese(II) ion, and for <b>3</b>, M is the zinc(II) ion). Both of them consist of 1D supramolecuar chains via π−π interactions. The structure of <b>2</b> also has the oxamido-bridged trinuclear [Mn<sup>II</sup>Cu<sup>II</sup><sub>2</sub>] structure units and consists of 2D layers formed by the linkage of copper(II) and manganese(II) atoms via the oxamido and μ<sub>1, 5</sub>-dca bridges. Complex <b>4</b> consists of oxamido-bridged tetranuclear [Fe<sup>II</sup><sub>2</sub>Cu<sup>II</sup><sub>2</sub>] molecules and arranges in 1D chains. Different co-ligands may result in different structures in this macrocyclic oxamide system. The variable-temperature magnetic susceptibility measurements (2−300 K) of <b>1</b> and <b>2</b> both show the pronounced antiferromagnetic interactions between the copper(II) and manganese(II) ions.