[Zurück]

N. Trendafilova, G. Nikolov, R. Kellner, H. Mikosch, G. Bauer, G. Bogatchev:
"Manifestation of the Jahn-Teller active vibrations in the vibronic spectra of tetracoordinate Cu2+, Ni2+ and Zn2+ chlorides";
Chemical Physics, 147 (1990), 2-3; S. 377 - 387.

An attempt is made to track the changes in the vibrational modes that are Jahn-Teller active of some pseudotetrahedral MCl42− ions. The infrared and Raman spectra of powder (Et4N)2MCl 4, M=Ni, Cu, Zn and of Cu- and Ni-doped (Et4N)2ZnCl4 were recorded both at room temperature and at 77, 100 and 170 K. The room temperature spectra show that for NiCl42− and CuCl42− if present the Jahn-Teller distortions are dynamically averaged and the transitions can be accounted for as intrasheet vibronic transitions. The low-temperature spectra however show splittings that are indicative of a low symmetry field thus suggestingthat at 77 K the NiCl42− and CuCl42− are vibronically stabilized in a static C2v field. The doped compound spectra reveal that the Zn matrix effect overrides the static Jahn-Teller distortions present in the free ion spectra. In the CuCl42− spectrum a band at 2700 cm−1 with side bands +v(a1), −v(t2s) was detected and it was assigned to the 2B2g→2B1g transition arising from the split 2T2 term in D2h site symmetry.

http://dx.doi.org/10.1016/0301-0104(90)85052-X