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)₃(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)₃(Im)(Phen)]⁺ in solution and their dynamics should include extensive sampling of vibrational motion and spin–orbit couplings.