Crystal Architectures and Magnetic Properties of Alkylferrocenium Salts with FnTCNQ (n = 0, 2, 4): Effect of Substituents on the Self-Assembled Structures

The crystal architecture and magnetic properties of the alkylferrocenium salts of tetracyanoquinodimethane (TCNQ)-type acceptors have been investigated using 1,1′-dimethyl-, 1,1′-diethyl-, 1,1′-diisopropyl-, tert-butyl-, and tert-pentyl-ferrocene as the donors. In all of the resulting salts, the donors and acceptors were stacked to form independent columns. The F4TCNQ salts had a D/A ratio of 1:1 and existed as hexagonal assembled structures composed of anion columns surrounded by cation columns. The F2TCNQ and TCNQ salts had a D/A ratio of 1:2 and existed as a rectangular arrangement of cation columns. Weak antiferromagnetic interactions were found to operate between the cations in these salts.