Chemical Control of spin-orbit coupling and charge-tranfer bands in Vacancy-Ordered Double Perovskites, Angew. Chem. Int. Ed., 2021, 60, 5184–5188. (DOI: 10.1002/anie.202013383)

Chemical Control of spin-orbit coupling and charge-tranfer bands in Vacancy-Ordered Double Perovskites, Angew. Chem. Int. Ed., 2021, 60, 5184–5188. (DOI: 10.1002/anie.202013383)

Vacancy-ordered double perovskites are attracting significant attention due to their chemical diversity and interesting optoelectronic properties. With a view to understanding both the optical and magnetic properties of these compounds, two series of RuIV halides are presented; A2RuCl6 and A2RuBr6, where A is K, NH4, Rb or Cs. We show that the optical properties and spin-orbit coupling (SOC) behavior can be tuned through changing the A cation and the halide. Within a series, the energy of the ligand-to-metal charge transfer increases as the unit cell expands with the larger A cation, and the band gaps are higher for the respective chlorides than for the bromides. The magnetic moments of the systems are temperature dependent due to a non-magnetic ground state with Jeff=0 caused by SOC. Ru-X covalency, and consequently, the de-localization of metal d-electrons, result in systematic trends of the SOC constants due to variations in the A cation and the halide anion.