Lanthanide Organometallic Compounds as Single-Molecule Magnets*

Organometallic sandwich compounds have played a leading role in the development of lanthanide chemistry. However, the magnetic properties of f-element organometallics have not been studied extensively, which is surprising given the prominent roles played by lanthanides in magnetic materials and their applications medical settings, notably MRI.

Our research is primarily concerned with the dynamic magnetic properties of lanthanide organometallic compounds and their use as single-molecule magnets (SMMs), a family of compounds that show magnet-like behaviour below a characteristic blocking temperature.

Since 2010, we have developed a large family of dysprosium SMMs based on cyclopentadienyl ligand environments, and we have used our findings to develop a working model that allows the blocking temperature to be increased in a rational way. The culmination of our work is a dysprosium metallocene SMM with a blocking temperature of 80 K, which is (currently) the only example to function above liquid nitrogen temperatures.

In this presentation, we will explore the relationship betweeen the dynamic magnetic properties of dysprosium sandwich compounds and their chemical environment. We are now focused on improving the SMM properties by studying a ligand type that is well-known to transition metal chemists but is extremely rare in the f-block: the four-membered ring cyclobutadienyl. Understanding these systems with the aid of multireference ab initio calculations has proven to be invaluable, and provides clues as to how SMMs that function at unprecedentedly high temperatures might be obtained.