The S 0 → S 1 excitation energy calculated with XMS-CASPT2(10,9)/ANO-S-VDZP for 1 and 2 are 4.42 and 4.52 eV, respectively. Both transitions are n → 𝜋 and have oscillator strengths of 0.0094 (1) and 0.0069 (2) based on their optimized equilibrium geometries. The S 0 → S 2 excitations have energies of 5.00 eV (1) and 5.68 eV (2) and are both 𝜋 → 𝜋 * transitions. The oscillator strengths of these transitions are 0 for 1 and 2. The S 0 → S 3 electronic excitations of 1 and 2 are 𝜋 → 𝜋 * transitions, with energies and oscillator strengths of 7.42 eV and 7.14 eV and 0.07 and 0.05, respectively. Including an ensemble of energetically accessible non-equilibrium geometries enabled our prediction of a full absorption spectrum. As such, we generated 500 Wigner-sampled-geometries and computed the S 0 ➝S n (n=1,2,3) vertical excitation energies and corresponding oscillator strengths for 1 and 2. Figure X shows an ensemble overlay of 1 and 2 and the absorption spectrum with normalized intensities using SA(4)-CASSCF(10,9)/ANO-S-VDZP. The λ max peaks near 190 nm correspond to S 0 → S 3 excitations and have the highest intensity. The n → 𝜋 * transition at 220 nm corresponds to an S 0 → S 2 excitation and has vanishing intensity. The S 0 → S 1 excitation for 1 and 2 (n → π * ) has a peak centered near 260 nm. While the intensity of this peak (shown in red) is substantially lower than that of the 𝜋 → 𝜋 * transition, it corresponds to the λ of the experimental light-source. The peaks corresponding to the second-and third-lowest excited state (shown in blue and yellow, respectively) correspond to excitation energies higher than the experimental light source. As such, we decided to focus on the S 1 -state to explore the static and dynamic components of the photo-decarbonylation reaction mechanism of 1 and 2.