Crystal structure and spectroscopic properties of N,N′-bis(8-quinolilethylenediamine)monochlorocopper(II) perchlorate

The crystal structure of the title compound, [Cu(nn)Cl]ClO4, where nn=N,N′-bis(8-quinolilethylenediamine) has been determined by X-ray diffraction using diffractometer data collection. The Cu atom was located from a Patterson synthesis and the remaining non-hydrogen atoms were found from a subsequent Fourier synthesis. The new compound crystallises in the monoclinic space group P21/n with a=15.647(3), b=9.775(2), c=14.156(3) Å, β=107.71(2)° and Z=4. The CuN4Cl chromophore forms an intermediate geometry between a distorted tetragonal pyramid and a distorted bipyramid trigonal. The polycrystalline and frozen solution ESR spectra are reported between 77 K and room temperature. The molecular g tensor in the frozen solution is best consistent with the square pyramidal distorted stereochemistry in which an N atom occupies the axial position. The ESR spectrum does not change with the temperature. Extended Hückel calculations show the unpaired electron predominantly in the dx2−y2 orbital, in accordance with the proposed geometry.