Cover Picture (Angew. Chem. Int. Ed. Engl. 13/14/1995)


original image

The cover picture shows the bowl-shaped structure of the highly strained tricycle, dilithium acepentalenediide (C atoms blue–gray, H atoms white). Accordinly, the as yet unknown neutral hydrocarbon, acepentalene, should also have a bowl-shaped structure. In the solid state the dilithium acepentalenediide forms dimeric contact ion triplets, in which the convex side of the two dianion fragments point towards each other; the lithium counterions (silver) are coordinatively saturated with dimethoxyethane ligands (O atoms red). The computer graphics were generated by Dr. H. Michaelsen with a “ray tracing” program (Persistence of Vision 2.2) on a Power Challenge L (Silicon Graphics). More about this unusual dianion is reported by A. de Meijere, D. Stalke et al. on page 1492ff.