Tetrathiafulvalene Dimer Merged with a Binuclear Ring of Sn and Sb: Synthesis and Molecular Structures Induced by Heteroatoms

Abstract

In this study, we describe the synthesis and characterization of dimeric tetrathiafulvalene (TTF) derivatives that are doubly bridged by Sn (1) and Sb (2a) atoms as a new class of organic‐inorganic hybrid compounds able to provide enhanced dimensionality in the solid state. The antimony heterocyclic framework was constructed by a simple Sn–Sb metal exchange reaction of a 1,4‐distannine moiety with p‐tolyl antimony dichloride (p‐tolSbCl2). Compound 2a was obtained in cis and trans forms as a stable configurational isomer. From X‐ray crystallographic analysis, there were three conformational isomers in which the tolyl rings were directed in the endo or exo direction. Crystal packing revealed a supramolecular three‐dimensional network through intermolecular short contacts of Sb···S and Sb···π. These packing forces gave a trans‐2aexo–exo conformation in the crystal, although the theoretical calculations predict its instability compared with other conformers. Cyclic voltammetry (CV) measurements of 1 and cis/trans‐2a revealed two pairs of reversible redox processes corresponding to the formation of TTF/TTF·+ and TTF·+/TTF2+. Furthermore, CV of cis/trans‐2a also revealed the reduction waves derived from the reduction of SbIII. Dicationic and tetracationic species were prepared by chemical oxidation, and their electronic structures were also investigated by electronic spectroscopy.