Exploring the computational design of anionic spin-crossover systems

Abstract

In this work, a systematic study on how the ligand design in the anionic spin-crossover system [Fe(OEt-L₁-pH)(NCS)₃]⁻ can be used to achieve a high degree of tuning of its transition temperature (T_1/2) is presented. Our calculations correctly reproduce the experimentally reported data and allow us to gain further and systematic insight on how to tune up or down the T_1/2 value. The axial thiocyanate ligand can be replaced by similar groups (NCO⁻, NCSe⁻ and NCBH₃⁻) that allows for a large change in the T_1/2 value, while a much finer degree of tuning can be achieved by functionalizing the para position of the pyridine groups. Altogether, [Fe(OEt-L₁-pH)(NCS)₃]⁻ offers a unique platform to explore how ligand design can be realized to prepare new anionic SCO materials with tailored properties.