Chemical Reduction of a Nanosized [6]Cyclo‐2,7‐naphthylene Macrocycle

Abstract

Chemical reduction of a naphthylene macrocycle, [6]cyclo-2,7-naphthylene ([6]CNAP, 1), with alkali metals, Li and K, revealed the accessibility of the doubly-reduced state of 1. The macrocyclic 1 2À anion was isolated in different coordination environments and crystallographically characterized. The single-crystal X-ray diffraction confirmed the formation of contact-ion complexes with one Li + and two K + ions in THF, and a "naked" dianion in the solvent-separated ion product with K + ions in the presence of 18-crown-6 ether. The detailed structural analysis of 1 2À showed that the pconjugation over the biaryl linkages between naphthylene panels were enhanced upon two-fold reduction, which was rationally explained by theoretical calculations.