Crystal structure and spectroscopic properties of oxalato (1,4,8,11-tetraazacyclotetradecane)chromium(III) perchlorate

The crystal structure of [Cr(ox)cyclam]ClO4 has been determined by X-ray crystallography. The macrocyclic cyclam is folded along the N(4) and N(11) direction with the four N atoms coordinated to the Cr atom and the two O atoms occupying the two remaining positions. The complex cation unit has its central Cr atom in a distorted octahedral coordination with two Cr–O and four Cr–N bonds at average distances 1.959 and 2.077 A° , respectively. The zero-phonon line in the sharp-line absorption spectrum splits into two components by 81 cm21. The UV-visible and IR spectra have also been measured. The spectral properties of the title complex reflect the bidentate coordination of oxalate and the cis-V configuration of the cyclam ligand. q 2004 Elsevier B.V. All rights reserved.