Structural Diversity of Lithium Neopentoxide Compounds

The reaction of LiN(SiMe₃)₂ with 1 equiv of HOCH₂CMe₃ (HONep) in toluene led to the formation of [Li(μ₃-ONep)]₈ (1). The complex adopts a novel dual-edge fused hexagon−square prismatic structure with a C_2v axis of rotation that relates the top and bottom eight-membered rings. Substituting the noncoordinating solvent toluene for a Lewis basic solvent (THF or py) led to the isolation of compounds of the general formula [Li(μ₃-ONep)]₄(solv)₃, where solv = THF (2) or py (3). The cube structures of 2 and 3 have one Li which is not solvated because of steric crowding of the ONep ligands. Multinuclear solid-state (⁶Li, ⁷Li, and ¹³C) MAS and solution-state (¹H, ⁷Li, and ¹³C) NMR studies were undertaken to verify the identity of the bulk powder and to determine the solution behavior of these compounds.