Synthesis and characterization of a 14-membered macrocyclic copper (II) complex

Macrocycles are an important class of ligands in transition metal chemistry since they can provide beneficial thermodynamic and kinetic properties to their metal complexes. There are a board range of applications for these types of ligands and their complexes, such as metal ion-selective reagents [1], precursors for luminescent compound formation, MRI contrast agents and radiopharmaceuticals [2].In this work, a new macrocyclic copper complex of 1,3,6,10,12,15-hexaazatricyclo[13.3.1.16,10]eicosane (ACE), [Cu(ACE)NO3]NO3, was prepared by template synthesis, followed by ion exchange reaction and its spectral and structural properties was investigated. The complex is an intermediate product which can be formed during the ion exchange reaction of its non-ionic [Cu(ACE)(NO3)2] compound. In the structure of the complex (figure 1), the copper atom has a distorted square pyramidal geometry with CuN5 environment. The complex has Jahn-Teller distortion.m.p. 199 °C. Anal. Calcd for C14H30CuN8O6 (%): C, 35.78; H, 6.43; N, 23.84. Found: C, 35.90; H, 6.51; N, 23.96. IR (KBr, cm−1): 3269 m (ν N−H), 2935 m (νas CH2), 2860 m (νs CH2), 1465 m (δas CH2), 1403 s (δs CH2), 1360 s (ν4 NO3), 1320 s (ν4 NO3free), 1268 m (ν1 NO3), 1086 m (ν2 NO3), 1046 m (ν C−N), 818 m (ν6 NO3).