We investigated the excited state of a ring-shaped dinuclear Re(I) diimine bis-carbonyl complex that shows promise with regard to efficient photosensitized reactions and multi-electron storage, using time-resolved infrared (TR-IR) vibrational spectroscopy and quantum chemical calculations. Anomalous peaks in the CO stretching region of the TR-IR spectrum were well reproduced by the calculations. It was found that metal-to-ligand charge transfer occurs only in one of the Re complex units, and that the excited state geometry is deformed relative to the ground state in order to relax the associated steric tension. This structural deformation generates the unique photophysical properties of the complex. (C) 2016 Elsevier B.V. All rights reserved.