Synthesis, Structure, and Electron-Donating Ability of 2,2:6,2"-Dioxatriphenylamine and Its Sulfur Analogue

2,2ʹ:6ʹ,2"-Dioxa- and dithia-triphenylamines 4a and 4b were prepared. Both compounds had a C2-like structure. The sulfur compound 4b had a more twisted structure than 4a; the dihedral angle between two edge phenyl rings was 43° for 4a, and 62° for 4b. The oxygen compound 4a had a reversible oxidation wave at +0.81 V vs SCE, whereas 4b had an irreversible peak at +1.14 V.