Synthesis, Structures, and Electrochemical Properties of Bis- and Tetrakis(diphenylphosphino)tetrathiafulvalenes Extended with an Anthraquinoid Spacer

Bis- and tetrakis(diphenylphosphino)tetrathiafulvalenes extended with an anthraquinoid spacer were successfully synthesized. X-ray structure analysis revealed that the phosphorus atoms adopt the typical distorted tetrahedral geometry. Their average C-P-C angles and phosphorus-carbon distances resemble those of diphenylphosphino-substituted TTF derivatives. The cyclic voltammograms consisted of one pair of irreversible, simultaneous two-electron transfer waves. A combination of cyclic voltammetry experiments and DFT calculations suggested the coexistence of two different reduction processes depending on the scan rate.