Über die Natur der Cu2+-Zentren im NH4Cl―die spektroskopische Untersuchung von Cu2+-dotiertem Hg(NH3)2Cl2

The preparation of Hg(NH 3 ) 2 Cl 2 doped with a small amount of Cu 2+ is reported. The EPR and ligand field reflectance spectra indicate the presence of «CuCl 4 (NH 3 ) 2 » polyhedra with a compressed tetragonal geometry and confirm, that the centres in Cu 2+ doped NH 4 Cl possess the same geometry―as postulated earlier. The Cu 2+ centrs in Hg(NH 3 ) 2 Cl 2 are less compressed than those in NH 4 Cl, however, as could be deduced from the copper(II) hyperfine values, which are strongly influenced by the quite different admixture of the metal 4s orbital into the A 1g (d z 2) ground state in the two cases, and from the comparable energies of the d-d transitions