Structures of 1,1′,3,3′-Tetra(2-methyl-2-nonyl)ferrocenium(1+) Oxoanion(1−) Salts. Layered Materials with Alternating Ionic and Low-Dielectric Paraffin-Like Domains Through Which Anion Diffusion is Rapid

The unprecedented interdigitated and layered structures of 1,1′,3,3′-tetra­(2-methyl-2-nonyl)­ferrocene (DEC) and the oxoanion ferrocenium salts DEC+NO3–, DEC+ClO4–, and DEC+ReO4– were determined by single-crystal X-ray diffraction. The four structures are similar except that the three DEC+ salts have layers of XOn– oxoanions stuffed between the layers of interdigitated ferrocenium ions. The perpendicular distances between layers of Fe atoms are 8.530, 9.108, 9.009, and 9.158 Å for DEC, DEC+NO3–, DEC+ClO4–, and DEC+ReO4–, respectively. The structures also contain layers of rigorously coplanar Fe and X atoms that are tilted 65.4, 75.9, 61.9, and 61.1° from the aforementioned layers of Fe atoms for DEC, DEC+NO3–, DEC+ClO4–, and DEC+ReO4–, respectively. The local environments of the XOn– oxoanions consist of networks of C–H···O hydrogen bonds, and the structures exhibit channels through which these anions could diffuse. Facile diffusion of these anions in thin films of DEC+XOn–, with structures that appear to resemble the crystal structures, has been demonstrated.