| Abstract
| - Corannulene (C20H10), with a bowl shape and a curvature similar to that in C60, is slightly flattened in its [Cp*Ru(η6-C20H10)][SbF6] (3[SbF6]) complex, but it is essentially flat in [(Cp*Ru)2(μ2-η6:η6-C20H10)][SbF6]2 (4[SbF6]2). The two η6-coordinated Cp*Ru+ units make the corannulene in 42+ sufficiently flexible that its shape in the solid state is controlled by crystal-packing energies.
- The corannulene complex [Cp*Ru(η6-C20H10)]+ (3+; where Cp* = η5-C5Me5), prepared bythe reaction of [Cp*Ru(μ3-Cl)]4 with Ag+ and the curved-surface buckybowl C20H10 (1), hasa structure in which the bowl is slightly flattened as compared with the case for freecorannulene. The corannulene unit in [(Cp*Ru)2(μ2-η6:η6-C20H10)][PF6]2 (4[PF6]2), containingtwo η6-{Cp*Ru}+ units coordinated on opposite sides of the corannulene, is flattenedsubstantially more. The X-ray-determined structure of the corresponding SbF6- salt,[(Cp*Ru)2(μ2-η6:η6-C20H10)][SbF6]2 (4[SbF6]2), shows that the corannulene bowl is almostcompletely flat. Low-temperature NMR studies of the analogous 1,2,5,6-tetramethylcorannulene complex [(Cp*Ru)2(μ2-η6:η6-C20H6Me4)]2+ (62+) show that there is a very low barrierto inversion of the bowl, even at −90 °C. Computational investigations reproduce the majorstructural features of 3+ and 42+ and account for the low corannulene inversion barrier in42+.
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