Redox-Active Cu(I) Complex with Bi-functionalized Tetrathiafulvalene Ligand

Multifunctionalized tetrathiafulvalenes (TTFs) and their transition metal complexes have been widely studied to develop the materials with electric-magnetic hybrid proper-ties.1 Central concept for achieving the hybrid properties is the proper packing of the complexes in which TTF planes and metals are suitably arranged to provide the exchange interactions of electric π orbitals for conductivity and magnetic d orbitals for magnetic properties, respectively. TTF should be appropriately functionalized to form such a fused metal complex as well as to tune its structure and properties. Attempts have been made to functionalize TTFs, whose metal complexes maintain electroactivity similarly to TTF, with phosphine,2 dithiolate,1b pyridine,3 and acetyl-acetonate.4 Interest in the usage of carboxylate for the function-alization of TTFs has grown because of its hydrogen-bond-ing ability,5a pH dependence,5b and the forte of forming many useful metal organic frames (MOFs).6 The metal coordination compounds with bicarboxylate-TTF or tetra-carboxylate-TTF ligand have been recently reported, in which they exhibited the electrochemically and magnetically active properties, and the possibilities of potential appli-cations for the battery-electrode materials.7 In those com-plexes, the TTF derivatives bind to metal ions through the carboxylate groups. In this study, we use a TTF bi-function-alized with sulfide and carboxylate groups (Scheme 1) to study its ability to form a metal complex with Cu(I) and to investigate the structure and electrochemical activity of the metal complex