Excited-states of a rhenium carbonyl diimine complex: solvation models, spin–orbit coupling, and vibrational sampling effects

Abstract

We present a quantum-chemical investigation of the excited states of the complex [Re(CO)(Im)(Phen)] (Im = imidazole; Phen = 1,10-phenanthroline) in solution including spin-orbit couplings and vibrational sampling. To this aim, we implemented electrostatic embedding quantum mechanics/molecular mechanics (QM/MM) in the Amsterdam Density Functional program suite, suitable for time-dependent density functional calculations including spin-orbit couplings. The new implementation is employed to simulate the absorption spectrum of the complex, which is compared to the results of implicit continuum solvation and frozen-density embedding. Molecular dynamics simulations are used to sample the ground state conformations in solution. The results demonstrate that any study of the excited states of [Re(CO)(Im)(Phen)] in solution and their dynamics should include extensive sampling of vibrational motion and spin-orbit couplings.

Excited‐State Reactivity of [Mn(im)(CO)3(phen)]+: A Structural Exploration

“…). Note that a proper comparison with the experimental spectrum can only be achieved when several conformers of the complex are considered . As expected from the molecular orbital picture (see previous section), both complexes present very similar features.…”

“…The TD‐DFT/TDA calculated absorption spectra of [Re(im)(CO) 3 (phen)] + in water has been previously discussed . The absorption spectra of [Mn(im)(CO) 3 (phen)] + computed under the same conditions is presented here in Figure together with the one of [Re(im)(CO) 3 (phen)] + for comparison.…”

Charge‐Transfer versus Charge‐Separated Triplet Excited States of [ReI(dmp)(CO)3(His124)(Trp122)]+ in Water and in Modified Pseudomonas aeruginosa Azurin Protein

“…In particular, for 3 MLCT, in which the electron density was drawn from the metal to the dmp ligand, charges were obtained by considering a −1 charged dmp moiety, whereas a +1 positive charge was redistributed equally to each carbonyl CO and the Re atom. This choice was justified by the fact that Re and CO ligands were strongly correlated with hole density spread over those units in both triplet and singlet MLCT states . In the case of CS, instead, a positively charged Trp moiety was considered together with the negatively charged dmp.…”

“…The excited‐state properties of isolated metal complexes are the subject of numerous computational investigations based on electronic structure theory and quantum dynamics for the interpretation of their fascinating behavior . However, only a few pioneering studies have been devoted to the effects of the molecular surroundings on these properties . As a paradigmatic example, one can cite the study of the emission properties and absorption spectra of organometallic Ru II DNA intercalators or of a Re I complex probe for DNA‐mediated charge transport …”

“…However, only a few pioneering studies have been devoted to the effects of the molecular surroundings on these properties . As a paradigmatic example, one can cite the study of the emission properties and absorption spectra of organometallic Ru II DNA intercalators or of a Re I complex probe for DNA‐mediated charge transport …”