Sulfur-rich CpCo(dithiolene) complexes: Isostructural or non-isostructural couples of CpCo(III) with CpNi(III) dithiolene complexes

Eight new sulfur-rich [CpCo(dithiolene)] complexes were synthesized from [Zn(dmit)2]2− as a starting material. The structures, electrochemical behavior and electronic absorption spectra of the sulfur-rich [CpCo(S2C2S2Y)] complexes could be compared with the early data of analogous Ni complexes. [CpCo(pddt)] (Y = –(CH2)3–), [CpCo(dpdt)] (Y = –CH2C(CH2)CH2–), [CpCo(bddt)] (Y = –(CH2)4–), [CpCo(dtdt)] (Y = –CH2SCH2–) and [CpCo(poddt)] (Y = –CH2C(O)CH2–) crystallized in all isostructural with the corresponding paramagnetic [CpNi(dithiolene)]radical dot complexes, but [CpCo(dmid)] (Y = Cdouble bond; length as m-dashO), [CpCo(dddt)] (Y = –(CH2)2–) and [CpCo(F2pddt)] (Y = –CH2CF2CH2–) crystallized in non-isostructural with them. These molecules are associated with intermolecular short S⋯S contacts in the crystals. [CpCo(F2pddt)] did not show any remarkable S⋯S contacts but indicated interesting fluorine segregation and Cp⋯Cp face-to-face interactions. Redox potentials of [CpCo(dithiolene)] complexes were obtained with the cyclic voltammetry measurements and dimerized by electrochemical oxidations. Electronic absorption spectra of [CpCo(dithiolene)] complexes showed visible absorption in the range of 585–701 nm as lowest energy wavelengths (ɛ = 9800–11,800 M−1 cm−1) in solutions, and they were higher energy than those of [CpNi(dithiolene)]radical dot complexes (near-IR).