Magnetic Anisotropy in Heterobimetallic Complexes.

Control of spin-orbit coupling enables the targeted modulation of coherence, catalytic, and magnetic properties in metal complexes. In this Forum, we describe our approach to exerting synthetic control over spin-orbit coupling by using heavy diamagnetic main-group metals as an external source of spin-orbit coupling. By binding these elements to first-row transition metals, we can probe the manifestation of spin-orbit coupling in their properties, by breaking spin-orbit coupling into a two-atom phenomenon. Within this approach, we focus on metal-ligand covalency and the importance of covalency in spin-orbit coupling transfer. To fully understand these systems, we need to design molecules that support careful decoupling of the influences of ligand field geometry and ligand-derived spin-orbit coupling on the magnetic anisotropy of paramagnetic transition metals. These design criteria, along with the advantages of bimetallic species, are described. We anticipate this perspective will offer a fundamental model for using two-metal systems for engendering spin-orbit coupling.