Ln–Pt electron polarization effects on the magnetic relaxation of heterometallic Ho– and Er–Pt complexes

Abstract

Heterometallic Ln-Pt complexes, with the formula [Ln2Pt3(H2O)2(SAc)12] (Ln = Ho(1), Er(2); SAc = thioacetate), were synthesized. From natural bond orbital (NBO) and local orbital locator (LOL) analyses and X-ray absorption fine structure (XAFS) measurements, it was clear that the Ln-Pt interactions or electron polarization occurred. Butterfly-type hysteresis was observed for both 1 and 2. 1 and 2 underwent field-induced slow magnetic relaxation up to 4 K. These magnetic properties were induced by Ln-Pt electron polarization.

Importance of Axial Symmetry in Elucidating Lanthanide–Transition Metal Interactions

“…This effect is more pronounced in Pt than in Pd due to the larger spatial extension of the 5d z 2 orbital compared to the 4d z 2 orbital. Our conclusion agrees with a recently reported localized orbital bonding simulation performed on a La–Pd and La–Pt complexes with similar ligands. , …”

“…Yamashita et al investigated dimeric compounds with similar ligands, exhibiting shorter Ln–Pd (Ln = Gd) and Ln–Pt (Ln = Gd, Tb, Ho, Er) distances compared to our complexes. They have experimentally investigated their compounds using UV−vis and XANES spectroscopy, invariably obtaining a shift in the Pt L 3 -edge that suggested a coordination geometry of Pt 2+ approaching square pyramidal. − Moreover, using DFT calculations on the La-substituted structure, they have corroborated that an interaction between the coordinated lanthanide and Pd or Pt is present, and that the higher radial extension of the 5d z 2 orbital of Pt compared to the 4d z 2 orbital of Pd enhances the polarization of the transition metal ion . However, to the best of our knowledge, the only CF investigation performed so far on a complex containing the Ln–Pd interaction was done on GdPd .…”

“…22−25 Moreover, using DFT calculations on the Lasubstituted structure, they have corroborated that an interaction between the coordinated lanthanide and Pd or Pt is present, and that the higher radial extension of the 5d z 2 orbital of Pt compared to the 4d z 2 orbital of Pd enhances the polarization of the transition metal ion. 25 However, to the best of our knowledge, the only CF investigation performed so far on a complex containing the Ln−Pd interaction was done on GdPd. 19 Gd 3+ is has a half-filled (4f 7 ) configuration, which yields typical CF splittings orders of magnitude smaller compared to the other paramagnetic lanthanide complexes.…”

“…Our conclusion agrees with a recently reported localized orbital bonding simulation performed on a La−Pd and La−Pt complexes with similar ligands. 22,25 The set of CF parameters that we extracted allowed the excellent simulation of the static magnetic properties (χT and magnetization curves, Figures S21 and S22). For all the complexes, the χT curves approach the Curie constant at around 100 K, testifying to the relatively small splitting of the ground multiplet compared to the thermal energy at room temperature.…”

“…Recently, great attention has been devoted in the study of the interaction between lanthanide ions and diamagnetic transition metals, particularly Pt 2+ and Pd 2+ . Paddlewheel metalloligands have been employed to synthesize mononuclear and polynuclear − lanthanide complexes exhibiting the Ln–Pd or Ln–Pt interaction.…”