Molecular curvature tradeoffs: Bending a planar trimercury unit over bowl-shaped polyaromatic hydrocarbons

The reactions of three bowl-shaped polyaromatic hydrocarbons, namely 1,2,5,6-tetramethylcorannulene (C24H18), dibenzo[a,g]corannulene (C28H14), and bicorannulenyl (C40H18), with the highly electrophilic trimercury complex (C18F12Hg3 or [Hg3]) resulted in the formation of 1D extended binary π-adducts, [Hg3·C24H18] (1), [Hg3·C28H14] (2), and [(Hg3)2·C40H18] (3), having molecules of polyarenes alternating with those of [Hg3] in the solid state. In 1−3, the [Hg3] unit is located over the central five-membered ring of the corannulene core adding to the rare examples of a multiple metal coordination to the inner surface of buckybowls. Upon coordination, the planar [Hg3] unit and the bowl-shaped polyaromatic hydrocarbons attempt to match the geometric characteristics of each other. Thus, bending of the planar surface of [Hg3] ranging from 6.6° in 1 to 17.0° in 2 and flattening of π-bowls by 14–22% of their initial depth is observed in the products reported here.

Bending the flat molecule and flattening the curved molecule is Nature’s way of forming π-adducts between a planar trimercury complex and several bowl-shaped polyaromatic hydrocarbons. Maximizing the surface contacts illustrates the “mutual curvature adaptations” phenomenon.Figure optionsDownload as PowerPoint slideHighlights
► In the solid state, bowl-shaped polyaromatic hydrocarbons form 1D stacks with the highly electrophilic trimercury complex of the 1:1 composition
► The planar surface of the [Hg3] unit adopts a significantly bent configuration upon interaction with bowl-shaped polyaromatic templates
► Noticeable bowl flattening is observed in their π-adducts with the electrophilic trimercury complex.