Raman and far-i.r. spectra are reported and assigned for the solid complexes Cr(CO)3(π-arene)(arene = benzene, aniline, toluene, methyl benzoate, anisole, and hexamethylbenzene) and M(CO)3(π-mesitylene)(M = Cr, Mo, or W). For the benzene complex, discussion is based upon the factor group, but in the other cases the molecular point-symmetry proves to be an adequate approximation. C3v local symmetry is an inadequate approximation when discussing the skeletal modes of complexes of monsubstituted arenes.