Characteristic patterns of infrared bands in the 7,(CO) region have been observed in the time-resolved infrared (TRIR) spectra of fac-rhenium tricarbonyl complexes that allow for identification of transient states that result following laser flash excitation. These patterns can be interpreted by combining experimental TRIR data with density functional theory (DFT) calculations. The DFT calculations are particularly valuable as they provide vibrational energy shifts between the ground and excited states and an analysis of the electronic interactions in terms of the orbitals involved in the excitation. TRIR and DFT results for four different transient excited states. intraligand pi -->pi*, metal-to-ligand charge transfer (MLCT), intramolecular (dpi-Opi) --> pi* excited states, and a redox-separated (RS state), are presented here. A unique example of competing excited states Studied by TRIR is also presented. The complexes studied include fac-[Re-1(CO)3(Me(2)dppz)(4-Etpy)](+), fac-[Re-1(CO)(3)(bpy)(4-Etpy)](+),fac-[Re-1(CO)(3)(4,4'-(CH3)(2)bpy)(OQD)],fac-[Re-1(CO)(3)(Me(2)dppz)(py-PTZ)](+), and fac-[Re-1(CO)(3)(dppz)(py-PTZ)](+) (Me(2)ppz is dimethyl dipyrido[3,2-a:2',3'-c]phenazine; dppz is dipyrido[3,2-a:2',3'-c]phenazine; 4Etpy is 4-ethylpyridine; bpy is 2,2'-bipyridine; 4,4'-(CH3)(2)bpy is 4,4'-(CH3)-2,2'bipyridine: OQD is 1-methyl-6-oxyquinone; py-PTZ is 10-(4-picolyl)phenothiazine). In addition to the DFT studies on the lowest triplet states probed by TRIR spectroscopy, time-dependent DFT (TD-DFT) calculations were also performed to analyze several of the lowest singlet and triplet excited states for each of the complexes.