Template-directed synthesis of macrocyclic copper(II) complexes of diazacyclam, 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane

Template reaction of copper(II) nitrate with N-(2-aminoethyl)-1,3-diaminopropane and formaldehyde yields a macrocyclic copper(II) complex of 1,3,6,10,12,15-hexaazatricyclo[13.3.1.1^6,10]eicosane (L), [CuL(NO₃)₂] (1). Replacement of nitrate with perchlorate gives [CuL(ClO₄)₂] (2). These complexes have been characterized by FT-IR and Raman spectroscopies, electronic absorption, cyclic voltammetry, and X-ray crystallography. The crystal structure of 1 shows that copper has distorted octahedral geometry with two secondary and two tertiary amines of the macrocycle and two oxygen atoms from nitrate coordinating the axial positions. The copper in 2 has the same geometry with axial positions occupied by one oxygen atom of perchlorate. Copper lies on the plane of four coordinated nitrogen atoms and there is no rms deviation from this plane. Cyclic voltammetry of 1 and 2 gives two one-electron waves corresponding to Cu^II/Cu^III (?0.75,??0.72) and Cu^II/Cu^I (0.48, 0.24) processes. For understanding of geometry parameters in diazacyclam-based copper(II) complexes, a survey on complexes from CSD structures is presented. In this study the macrocycle hole size was estimated by ionic radii of metal ions located inside of it.