Synthesis, Structure, and Magnetism of Tris(amide) [Ln{N(SiMe3 )2 }3 ]1- Complexes of the Non-traditional +2 Lanthanide Ions

Austin J Ryan; Lucy E Darago; Sree Ganesh Balasubramani; Guo P Chen; Joseph W Ziller; Filipp Furche; Jeffrey R Long; William J Evans

doi:10.1002/chem.201800610

Synthesis, Structure, and Magnetism of Tris(amide) [Ln{N(SiMe₃ )₂ }₃ ]^1- Complexes of the Non-traditional +2 Lanthanide Ions

Chemistry. 2018 May 28;24(30):7702-7709. doi: 10.1002/chem.201800610. Epub 2018 May 3.

Authors

Austin J Ryan¹, Lucy E Darago², Sree Ganesh Balasubramani¹, Guo P Chen¹, Joseph W Ziller¹, Filipp Furche¹, Jeffrey R Long³, William J Evans¹

Affiliations

¹ Department of Chemistry, University of California, Irvine, 1102 Natural Sciences II, Irvine, CA, 92697-2025, USA.
² Department of Chemistry, University of California, Berkeley, Berkeley, CA, 94720, USA.
³ Departments of Chemistry and Chemical and Biomolecular Engineering, University of California, Berkeley and Materials Sciences Division, Lawrence Berkeley National Laboratory, Berkeley, CA, 94720, USA.

PMID: 29490123
DOI: 10.1002/chem.201800610

Abstract

A new series of Ln²⁺ complexes has been synthesized that overturns two previous generalizations in rare-earth metal reduction chemistry: that amide ligands do not form isolable complexes of the highly reducing non-traditional Ln²⁺ ions, and that yttrium is a good model for the late lanthanides in these reductive reactions. Reduction of Ln(NR₂ )₃ (R=SiMe₃ ) complexes in THF under Ar with M=K or Rb in the presence of 2.2.2-cryptand (crypt) forms crystallographically characterizable [M(crypt)][Ln(NR₂ )₃ ] complexes not only for the traditional Tm²⁺ ion and the configurational crossover ions, Nd²⁺ and Dy²⁺ , but also for the non-traditional Gd²⁺ , Tb²⁺ , Ho²⁺ , and Er²⁺ ions. Crystallographic data as well as UV/Vis, magnetic susceptibility, and density functional theory studies are consistent with the accessibility of 4fⁿ 5d¹ configurations for Ln²⁺ ions in this tris(silylamide) ligand environment. The Dy²⁺ complex, [K(crypt)][Dy(NR₂ )₃ ], has a higher magnetic moment than previously observed for any monometallic complex: 11.67 μ_B .

Keywords: amides; low-valent metals; magnetism; rare-earth metals; reductions.