Infrared and Raman spectra have been measured on the compounds Cr 4GaLiO 8, Cr 4InLiO 8, and Rh 4InLiO 8. These have the structure of spinel with 1:1 order on the tetrahedral sites. Predicted and measured spectra agree well and additional features due to ordering can be clearly seen. The two tetrahedra are crystallographically equivalent in the disordered spinel structure and nonequivalent in the ordered structure. It is shown that ordering only partially decouples the motions of the tetrahedra.