The 77 K emission spectra of 21 [Ru(L)(4)bpy](m+) complexes for which the Ru/bpy metal-to-ligand-charge-transfer ((MLCT)-M-3) excited-state energies vary from 12 500 to 18 500 cm(-1) have vibronic contributions to their bandshapes that implicate excited-state distortions in low frequency (if, hv(if) < 1000 cm(-1)), largely metal-ligand vibrational modes which most likely result from configurational mixing between the (MLCT)-M-3 and a higher energy metal centered ((LF)-L-3) excited state. The amplitudes of the If vibronic contributions are often comparable to, or sometimes greater than those of medium frequency (mf, hv(mf) > 1000 cm(-1)), largely bipyridine (bpy) vibrational modes, and for the [Ru(bpy)(3)](2+) and [Ru(NH3)(4)bpy](2+) complexes they are consistent with previously reported resonance-Raman (rR) parameters, However, far smaller If vibronic amplitudes in the rR parameters have been reported for [Os(bpy)(3)](2+), and this leads to a group frequency approach for interpreting the 77 K emission bandshapes of [Ru(L)(4)bpy](m+) complexes with the vibronic contributions from mf vibrational modes referenced to the [Os(bpy)(3)](2+) rR parameters (OB3 model) and the envelope of If vibronic components represented by a "progression" in an "equivalent" single vibrational mode (If1 model). The If1 model is referenced to rR parameters reported for [Ru(NH3)(4)bpy](2+). The observation of If vibronic components indicates that the MLCT excited-state potential energy surfaces of Ru-bpy complexes are distorted by LF/MLCT excited-state/excited-state configurational mixing, but the emission spectra only probe the region near the (MLCT)-M-3 potential energy minimum, and the mixing can lead to larger distortions elsewhere with potential photochemical implications: (a) such distortions may labilize the (MLCT)-M-3 excited state; and (b) the If vibrational modes may contribute to a temperature dependent pathway for nonradiative relaxation.