A Room-Temperature Stable Y(II) Aryloxide: Using Steric Saturation to Kinetically Stabilize Y(II) Complexes
Samuel A. Moehring, Matthias E. Miehlich, Christopher J. Hoerger, Karsten Meyer, Joseph W. Ziller, William J. Evans
Abstract
The utility of the bulky aryloxide ligands 2,6-Ad2-4-Me-C6H2O– (Ad,Ad,MeArO–) and 2,6-Ad2-4-t-Bu-C6H2O– (Ad,Ad,t-BuArO–; Ad = 1-adamantyl) for stabilizing the Y(II) ion is reported and compared with the results with 2,6-t-Bu2-4-Me-C6H2O– (Ar′O–). In contrast to the reduction product obtained from reducing Y(OAr′)3 with potassium graphite, which is only stable in solution for 60 s at room temperature, KC8 reduction of Y(OArAd,Ad,t-Bu)3 in THF in the presence of 2.2.2-cryptand (crypt) produces the room-temperature stable, crystallographically characterizable Y(II) aryloxide [K(crypt)][Y(OArAd,Ad,t-Bu)3]. The X-band EPR spectrum at 77 K shows an axial pattern with resonances centered at g⊥ = 1.97 and g∥ = 2.00 and hyperfine coupling constants of A⊥ = 156.5 G and A∥ = 147.8 G and at room temperature shows an isotropic pattern with giso = 1.98 and Aiso = 153.3 G, which is consistent with an S = 1/2 spin system with nuclear spin I = 1/2 for the 89Y isotope (100% natural abundance).