1,1-Di(9-fluorenyl)ethanol, a by-product from the acetylation of 9-fluorenyllithium

Treatment of 9-fluorenyllithium with acetyl chloride produces 9-acetylfluor ene, (I), and several by-products. Among them is a compound unequivocally i dentified for the first time as the addition product of (I) with 9-fluoreny llithium, 1,1-di(9-fluorenyl)ethanol, C28H22O, (II). The two fluorene-ring planes of (II) are essentially perpendicular [89.90 (9)degrees]. A number o f intermolecular non-bonding distances are well within or close to the sum of their respective van der Waals radii and may be responsible for the rare ly observed large bowing of one of the fluorene rings. This bowing apparent ly arises from two molecules impinging on the convex face of the bowed ring , augmented by hydrogen bonding between the peripheral pi electrons of the concave face and the hydroxyl H atom of another molecule adjacent to that f ace.