Rational Design of Transition Metal Based Molecular Spin State Switches: Tuning the High Spin to Low Spin Transition Rate by Ligand Substitution

The effect of substitution in the axial 4' position by electron withdrawing (EW) and donating (ED) groups on the ground and excited state properties of the complex is investigated in a systematic study. DFT calculations are used to determine the geometric and electronic structures of the substituted complexes, and these calculated results were compared to experimental results from stationary and time-resolved spectroscopy. The question how this interplay of theory and experiment can be used in the context of ligand engineering is also considered.