Synthesis, Crystal Structure and Magnetic Properties of Heterodimetallic Re IV Cu II Complexes

The two rhenium( IV )‐copper( II ) heterometallic complexes [CuL β ][ReCl 4 (ox)] · DMF ( 1 ) and [(CuL α ) 2 Cl][ReCl 4 (ox)]Cl ( 2 ) (L β = N ‐ dl ‐5,7,7,12,14,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4,11‐diene and L α = N‐dl ‐5,7,7,12,12,14‐hexamethyl‐1,4,8,11‐tetraazacyclotetradeca‐4,14‐diene) were synthesized, and the crystal structures of both compounds were determined at 173(2) K. Complex 1 crystallizes in a monoclinic space group P 2 1 , with a = 9.365(2) Å, b = 15.150(2) Å, c = 10.776(1) Å, β = 110.01(1)°, Z = 2, whereas 2 crystallizes in an orthorhombic space group Pca 2 1 with a = 16.660(5) Å, b = 16.017(5) Å, c = 17.066(5) Å, and Z = 4. The CuL β macrocycle cation is approximately planar and coordinated from above and below by [ReCl 4 (ox)] 2– units through the bis(bidentate) oxalato ligands. It features an oxalato‐bridged heterometallic Re IV –Cu II zigzag chain, the shortest intrachain metal–metal distances are Re ··· Cu = 5.568(2) and 5.870(2) Å in the direction of the b axis. The crystal structure of 2 consists of dinuclear complex cations [(CuL α ) 2 Cl] 3+ with [ReCl 4 ox] 2– and isolated Cl – as counter anions. Cu atoms in CuL α are only fivefold coordinated in a square pyramidal surrounding, and the cations (CuL α ) 2+ are connected in pairs by chloride. The intramolecular Cu ··· Cu separation is 4.885(3) Å, the shortest Re ··· Cu distance is 7.612(3) Å. The magnetic behavior of 1 and 2 has been investigated over the temperature range 1.7–300 K. Compound 1 behaves like a ferrimagnetic Cu II ‐Re IV dimetallic, one–dimensional chain with intrachain antiferromagnetic coupling. Compound 2 shows weak antiferromagnetic interactions within the Cu II –Cu II units. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2005)