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

Abstract

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 XO_<i>n</i>^– 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 XO_<i>n</i>^– 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⁺XO_<i>n</i>^–, with structures that appear to resemble the crystal structures, has been demonstrated