1D copper(II) and zinc(II) coordination polymers containing an unusual twisted oxalate bridge

Two new copper(II) complexes, Cu(L1)(ClO4)2 (1), {[(μ-oxalate)Cu(L1)] · 5H2O}n (2), and a zinc(II) complex, {[(μ-oxalate)Zn(L2)] · 3H2O · 0.5DMF}n (3) (L = 3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,01.18,07.12]docosane), have been synthesized and characterized by X-ray crystallography. In 1, the ligand conformation is planar, and the octahedral coordination about the copper(II) ion is completed by weakly interacting ClO 4 - ions. In 2 and 3, bridging oxalate ligands coordinate to copper(II) or zinc(II) ions in an unusually twisted bis-monodentate (trans-1,1′-bicoordination) mode. gidity and steric hindrance of macrocycles L1 and L2 by the introduction of two cyclohexane rings and methyl groups on a cyclam (1,4,8,11-tetraazacyclotetradecane) skeleton cause the bridging oxalate ligands to adopt such unusual geometries in 2 and 3.