The versatile NO2- ligand is a chelating, bidentate ligand in the high symmetry M2M'Eu(NO2)(6) (M = Cs, Rb; M' = Na, Li) systems. The investigation of the vibronic structure and energy levels of these systems is of interest for comparison with the abundant data from Cs2NaEuX6 ( X = F, Cl) crystals. The vibrational structure in the electronic emission spectra of the hexanitritolanthanates has been investigated from the analysis of the 10 K and 100 K spectra. Most of the vibronic intensity of the D-5(0) -> F-7(0), F-7(2) transitions is due to low energy skeletal modes which correlate with tau(u) (T-h) infrared vibrations. The energy levels derived from the vibronic analysis indicate a weak crystal field in these systems. (C) 2010 Elsevier B. V. All rights reserved.