The first example of a lanthanide metallocenophane complex has been isolated as [Li(THF)][DyFcLi(THF)] (1). The molecular structure of complex 1 differs dramatically from those of main group and transition metal ferrocenophane complexes and features a distorted trigonal prismatic geometry around the Dy(III) ion and close intramolecular Dy···Fe distances. Furthermore, complex 1 exhibits all characteristics of a soft single-molecule magnet.

A rare example of an organometallic terbium single-ion magnet is reported. A Tb -[1]ferrocenophane complex displays a larger barrier to magnetization reversal than its isostructural Dy analogue, which is reminiscent of trends observed for lanthanide-bis-phthalocyanine complexes. Detailed ab initio calculations support the experimental observations and suggest a significantly larger ground-state stabilization for the non-Kramers ion Tb in the Tb complex than for the Kramers-ion Dy in the Dy complex.

Lanthanide ferrocenophanes are an intriguing class of organometallic complexes that feature rare six-coordinate trigonal prismatic coordination environments of 4f elements with close intramolecular proximity to iron ions.