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) (Lp = 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 P2 1 , with a = 9.365(2) A, b = 15.150(2) A, c = 10.776(1) A, β = 110.01(1)°, Z = 2, whereas 2 crystallizes in an orthorhombic space group Pca2 1 with a = 16.660(5) A, b = 16.017(5) A, c = 17.066(5) A, and Z = 4. The CuLp 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 I V -Cu I I zigzag chain, the shortest intrachain metal-metal distances are Re...Cu = 5.568(2) and 5.870(2) A in the direction of the b axis. The crystal structure of 2 consists of dinuclear complex cations [(CuL α ) 2 Cl] 3 + with [Re-Cl 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) A, the shortest Re...Cu distance is 7.612(3) A. 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 I I -Re I V dimetallic, one-dimensional chain with intrachain antiferromagnetic coupling. Compound 2 shows weak antiferromgunetic interactions within the Cu I I -Cu I I units.