DFT calculations of light‐induced excited states and comparison with time‐resolved crystallographic results

DFT calculations of the ground and first excited states of several transition metal complexes have been performed to complement time‐resolved diffraction experiments. The results from different functionals and relativistic treatments are tested against both diffraction and spectroscopic values. Calculations of the d8–d8complex [Pt2(pyrophosphite)4]4−quantitatively reproduce metal–metal shortening on excitation to the triplet state and support bond formation between the two metal centers, as do calculations on [Rh2(1,3‐diisocyanopropane)4]2+. Results on homoleptic and heteroleptic copper(I) 2,9‐dimethyl−1,10‐phenanthroline (dmp) complexes, which are investigated because of their potential for solar energy capture, confirm considerable molecular deformations on excitation. The distortion calculated for the isolated complex [Cu(dmp)(dmpe)]+(dmpe=1,2‐bis(dimethylphosphino)ethane) is significantly larger than observed in the crystal, indicating the constraining effect of the crystalline environment. The change in the net charge of the Cu atom upon photo‐induced metal‐to‐ligand charge transfer is less than 0.2 e, showing the limitations of the formal Cu(I)→Cu(II) designation. Electron density difference maps show a pronounced change in electronic structure of the Cu atom on excitation.