Probing Iron-Ligand interactions by combining modern high-resolution hard X-ray spectroscopy and density functional theory : a powerful methodology in cases where conventional methods fail / vorgelegt von Lukas Burkhardt ; [Prof. Dr. Matthias Bauer (Erstgutachter), Prof. Dr. Thomas Kühne (Zweitgutachter), Jun. Prof. Dr. Stephan Hohloch (Drittprüfer)]