Isolation of Dysprosium and Yttrium Complexes of a Three-Electron Reduction Product in the Activation of Dinitrogen, the (N2)3− Radical

DyI (2) reacts with 2 equiv of KOAr (OAr = OC (6) H (3) (CMe (3) ) (2) -2, 6) under nitrogen to form not only the (N (2) ) (2-) complex, (ArO) (2) (THF) (2) Dy (2) (mu-eta (2): eta (2) -N (2) ), 1, but also complexes of similar formula with an added potassium ion, (ArO) (2) (THF) Dy (2) (mu-eta (2): eta (2) -N (2) ) K (THF) (6), 2, and (ArO) (2) (THF) Dy (2) (mu (3) -eta (2): eta (2): eta (2) -N (2) ) K (THF), 3. The 1. 396 (7) and 1. 402 (7) A N-N bond distances in 2 and 3, respectively, are consistent with an (N (2) ) (3-) ligand, but the high magnetic moment of 4f (9) Dy (3+) precluded definitive identification. The YN (SiMe (3) ) (2) (3) /K reduction system was used to synthesize yttrium analogues of 2 and 3, (Me (3) Si) (2) N (2) (THF) Y (2) (mu-eta (2): eta (2) -N (2) ) K (THF) (6) and (Me (3) Si) (2) N (2) (THF) Y (2) (mu (3) -eta (2): eta (2): eta (2) -N (2) ) K, that had similar N-N distances and allowed full characterization. EPR, Raman, and DFT studies are all consistent with the presence of (N (2) ) (3-) in these complexes. (15) N analogues were also prepared to confirm the spectroscopic assignments. The DFT studies suggest that the unpaired electron is localized primarily in a dinitrogen pi orbital isolated spatially, energetically, and by symmetry from the metal orbitals.