Upon formation of the photoproduct [Re(CO)2(CH3CN)(Pyta)(TPP))] + , no further dissociation of CO ligands is observed. As illustrated in Figure , the photoproduct undergoes excitation to the 3 MLCT1 state, where the primary geometrical alteration involves a slight elongation of the Re-CNCH3 bond by 0.03 Å compared to the ground-state structure. Upon progression to the 3 MLCT2 state via the 3 TS, the Re-CNCH3 bond exhibits a significant elongation of 0.34 Å. However, no substantial changes in other geometric parameters of the photoproduct are detected. It is noteworthy that the electronic nature of the excited state remains MLCT despite the Re-CNCH3 bond elongation of 0.34 Å. This behavior contrasts with the related [Re(CO)3(Pyta)(TPP))] + complex, where the excited-state character transitions from 3 MLCT to 3 MC upon a smaller bond elongation of 0.14 Å. Following the attainment of the 3 MLCT2 state, the geometry of the 1/3 MECP state connecting to the 3 MLCT2 state was explored. The 1/3 MECP geometry exhibits further elongation of the Re-CNCH3 bond, reaching 3.63 Å, with no significant changes in the other Re-CO bond lengths. However, an upward bending of the PPh3-Re-CO angle was observed, seemingly to accommodate the spatial displacement of CH3CN. This behavior parallels the structural distortions seen in the [Re(CO)3(Pyta)(TPP))] + complex, here the CO ligand is pushed away. These findings, indicating the absence of additional CO dissociation from the photoproduct, align well with experimental observations. The stability of the photoproduct and the release of only one CO ligand suggest that the [Re(CO)3(Pyta)(TPP))] + complex is limited to single CO dissociation. To achieve multiple CO dissociations, it would be necessary to explore Mn(I)-based PhotoCORMs, which will be addressed in future work. Figure6: Energy profile diagram of the photoproduct, reflecting the its phtostability.