In this cyclophane, a phosphine lone pair is forced into the center of an aromatic ring. Even though there is no bond between the phosphorus and the basal ring carbons, these atoms show strong spin-spin coupling in the carbon-13 NMR spectrum of the molecule. The phosphine is completely protected from ordinary chemical reagents: it is not oxidized by hydrogen peroxide or peracids, and it cannot even be protonated by strong anhydrous acids. When resolved, this and related propeller-shaped molecules display exceptionally high optical rotations. For a brief communication describing its synthesis, X-ray crystal structure, and properties, see "Synthesis and Structure of an in-Phosphaphane: Enforced Interaction of a Phosphine and an Aromatic Ring." R. A. Pascal, Jr., A. P. West, Jr., and D. Van Engen, J. Am. Chem. Soc. 1990, 112, 6406-6407.