A New Class Of Ln~(2+) Complexes, K(2.2.2-cryptand){Ln(OAr~(Ad'Me))_3mes}:Synthesis, Structure, Spectroscopy, and Theoretical Characterization

摘要

The recent isolation of [K(2.2.2-cryptand)][Cp'3Ln] [Ln = Y and all the lanthanides except Pm due to its radioactivity; Cp' = (C_5H_4SiMe_3)~(1-)] demonstrated for the first time that the entire lanthanide series can form molecular complexes with metals in the +2 oxidation state and that electronic ground state configurations of Ln~(2+) ions are affected by their coordination environments.1"6 The (Cp'3)~(3-) coordination environment is unique in that, to date, it is the only environment to allow isolation of Ln2+ complexes across the series.6,7 This work describes recent attempts to move beyond (Cp'3)~(3-)with the goal of isolating more stable examples of Ln2+ using a tris(aryloxide)mesitylene ligand, [(~(Ad'Me)OAr)_3mes]3~ in order to study its effects on the electronic structure of Ln~(2+) ions in complexes. Structural comparisons with the U~(2+) analog, [K(2.2.2-cryptand)]-{U[(~(Ad,Me)OAr)_3mes},8 will be made.