Characterization of a Kinetically Stable, Highly Ordered, Octameric Form of Lithium tert-Butoxide and Its Implications Regarding Aggregate Formation

The controlled reaction of molecular oxygen with hydrocarbon solutions of t BuLi results in the unexpected formation of the octameric species [( t BuOLi)8], 1 8 . Single-crystal X-ray diffraction studies indicate that the connectivity within 1 8 corresponds with the fusion of two face-opened tetrameric cubanes. Cryoscopic studies establish the stability of the octamer in benzene solution, but heating results in aggregate rearrangement to the commonly found prismatic hexameric form, 1 6 . Theoretical calculations confirm that the hexameric form is the thermodynamically favored aggregate.