Magnetic Properties of a Terbium–[1]Ferrocenophane Complex: Analogies between Lanthanide–Ferrocenophane and Lanthanide–Bis‐phthalocyanine Complexes

Abstract

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.

Axial Elongation of Mononuclear Lanthanide Metallocenophanes: Magnetic Properties of Dysprosium‐ and Terbium‐[1]Ruthenocenophane Complexes

“…The difference in the barriers height of 1 and 1 Fc complexes (ca 15 cm −1 ) is small, but the relaxation time is three orders of magnitude larger in 1 Fc than in 1 (Table S15). The larger angle between the main magnetic axes of the ground and 1 st excited doublet (0.44° in 1 Fc and 13° in 1 ) causes a larger transition magnetic moment matrix element connecting the opposite doublet components of the ground and 1 st excited KDs (1− and 2+ in Figure ) in 1 compared to 1 Fc which causes smaller relaxation times in the former. In contrast, the Tb 3+ ion (m j =±6) experiences a slight decrease of its axial CF terms and a larger decrease in its trigonal term (B 3 4 ) in going from 2 Fc to 2 .…”

“…We have previously disclosed the first example of a Dy‐[1]ferrocenophane complex, [Li(thf) 4 ][DyFc 3 Li 2 (thf) 2 ] (Fc=[(η 5 ‐C 5 H 4 ) 2 Fe] 2− ) ( 1 Fc ), which features an approximate trigonal prismatic coordination environment around the Dy 3+ ion and exhibited SMM behavior with a U of 110 cm −1 . A comparative study of its terbium‐analogue, [Li(thf) 4 ][TbFc 3 Li 2 (thf) 2 ] ( 2 Fc ) revealed a larger value of U (274 cm −1 ). This led us to suggest that there are analogies in magnetic properties between approximately C 3 symmetric Ln‐ferrocenophanes and C 4 symmetric [LnPc 2 ] − complexes.…”

The duality of electron localization and covalency in lanthanide and actinide metallocenes

“…52 Efforts to unravel the complex behavior of correlated electron systems also benet from investigations of selfcontained phenomena in single molecules that can be more precisely characterized using spectroscopy and theory. [53][54][55][56][57][58][59][60] Our recent work has shown that the metal-ligand covalency and multicongurational ground states can be probed experimentally in f-element coordination compounds with X-ray absorption spectroscopy, XAS, at the K-edges for the light atoms directly bound to metal centers (collectively referred to as ligand K-edge XAS). [61][62][63][64] The spectroscopic technique probes bound state transitions of core 1s electrons localized on the ligands to unoccupied molecular orbitals, which only have intensity if the nal state orbitals have ligand np character (n ¼ principal quantum number).…”

Axial Elongation of Mononuclear Lanthanide Metallocenophanes: Magnetic Properties of Dysprosium‐ and Terbium‐[1]Ruthenocenophane Complexes

“…Our group has astanding interest in studying Ln- [1]metallocenophanes and correlating changes in molecular structure with dynamic magnetic properties. [7] We have previously disclosed the first example of aD y- [1]ferrocenophane complex, [Li(thf) 4 ][DyFc 3 Li 2 (thf) 2 ](Fc = [(h 5 -C 5 H 4 ) 2 Fe] 2À )(1 Fc ), [8] which features an approximate trigonal prismatic coordination environment around the Dy 3+ ion and exhibited SMM behavior with a U of 110 cm À1 .Acomparative study of its terbium-analogue,[ Li(thf) 4 ][TbFc 3 Li 2 (thf) 2 ]( 2 Fc ) [9] revealed Scheme 1. Changes in U upon axial elongation/contraction in [LnPc] À/0/+ and Ln- [1]metallocenophane complexes.…”