STABLE HIGH-ORDER MOLECULAR SANDWICHES - HYDROCARBON POLYANION PAIRS WITH MULTIPLE LITHIUM IONS INSIDE AND OUT

Stable ten-component sandwich compounds have been characterized in whi ch four lithium ions reside between two tetraanions derived from coran nulene or its alkyl-substituted derivatives and four additional lithiu m ions decorate the exterior. In tetrahydrofuran solution, the four li thium ions inside the sandwich can exchange environments with the four external lithium atoms, but the two tetraanion decks of the sandwich never separate from one another on the time scale of nuclear magnetic resonance. Theoretical calculations point to a ''stacked bowl'' confor mation and a low energy barrier for synchronous double inversion of th e tetraanion bowls in the solvated sandwich compounds.