Bis‐Cyclooctatetraenyl Thulium(II): Highly Reducing Lanthanide Sandwich Single‐Molecule Magnets

Abstract Divalent lanthanide organometallics are well‐known highly reducing compounds usually used for single electron transfer reactivity and small molecule activation. Thus, their very reactive nature prevented for many years the study of their physical properties, such as magnetic studies on a reliable basis. Herein, the access to rare organometallic sandwich compounds of Tm II with the cyclooctatetraenyl (Cot) ligand impacts on the use of divalent organolanthanide compounds as an additional strategy for the design of performing Single Molecule Magnets (SMM). The first divalent thulium sandwich complex with f 13 configuration behaving as a single‐molecule magnet in absence of DC field is highlighted.