Electrochemical and spectroscopic techniques have been used to study the benzo‐, duro‐, tetrachloro‐, and p‐xyloquinone‐hydroquinone couples in nonaqueous solvents. The proton transfer reactions which are coupled to the electron transfer steps are elucidated. Oxidation of the hydroquinone leads to the protonated quinone species, while reduction of the quinones in the presence of a proton source gives mixtures of the corresponding hydroquinone, its conjugate base, and the free semiquinone, depending on the amount and strength of the proton donor used. Oxidation of the hydroquinones is postulated to proceed via a dimer of the one‐electron intermediate. Preliminary results are reported on the electrochemical behavior of solutions containing the quinhydrone charge‐transfer complex.

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A survey of methods for synthesizing tetrathioethylenes and a detailed discussion of a highly efficient new method, orthothiooxalate pyrolysis, are given. Syntheses of tetrathiafulvalene and a dihydrotetrathiafulvalene are described. The electrochemistry of representative tetrathioethylenes has been investigated and found to be characterized by two "clean" one-electron oxidations. E°values and the electronic absorption and esr spectra of the radical cations are discussed in relation to electronic and molecular structure. The ultraviolet spectra of tetrathioethylenes and their electrochemical properties can be rationalized by extended Hiickel calculations provided the 3d orbitals of sulfur are included in the basis sets. A search for conventional "electron-rich olefin" chemistry has given negative results. This lack of reactivity in contrast to oxygen and nitrogen analogs can also be rationalized by including d orbitals in the -bonding model.

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