Importance of Axial Symmetry in Elucidating Lanthanide-Transition Metal Interactions

In this paper, we experimentally study and model the electron donating character of an axial diamagnetic Pd 2+ ion in four metalloligated lanthanide complexes of formula [PPh 4 ][Ln{Pd(SAc) 4 } 2 ] (SAc - = thioacetate, Ln = Tb, Dy, Ho, and Er). A global model encompassing inelastic neutron scattering, torque magnetometry, and dc magnetometry allows to precisely determine the energy level structure of the complexes. Solid state nuclear magnetic resonance reveals a less donating character of Pd 2+ compared to the previously reported isostructural Pt 2+ -based complexes. Consequently, all complexes invariably show a lower crystal field strength compared to their Pt 2+ -analogues. The dynamic properties show an enhanced single molecule magnet behavior due to the suppression of quantum tunneling, in agreement with our model.