Jay, R.; Eckert, S.; Fondell, M.; Miedema, P.; Norell, J.; Pietzsch, A.; Quevedo, W.; Niskanen, J.; Kunnus, K.; Föhlisch, A.: The nature of frontier orbitals under systematic ligand exchange in (pseudo-)octahedral Fe(II) complexes. Physical Chemistry Chemical Physics 20 (2018), p. 27745-27751
10.1039/c8cp04341h
Open Access Version
Abstract:
Understanding and controlling properties of transition metal complexes is a crucial step towards tailoring materials for sustainable energy applications. In a systematic approach, we use resonant inelastic X-ray scattering to study the influence of ligand substitution on the valence electronic structure around an aqueous iron(II) center. Exchanging cyanide with 2-20-bipyridine ligands reshapes frontier orbitals in a way that reduces metal 3d charge delocalization onto the ligands. This net decrease of metal–ligand covalency results in lower metal-centered excited state energies in agreement with previously reported excited state dynamics. Furthermore, traces of solvent-effects were found indicating a varying interaction strength of the solvent with ligands of different character. Our results demonstrate how ligand exchange can be exploited to shape frontier orbitals of transition metal complexes in solution-phase chemistry; insights upon which future efforts can built when tailoring the functionality of photoactive systems for light-harvesting applications.