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

Abstract

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(S 2C 2S 2Y)] complexes could be compared with the early data of analogous Ni complexes. [CpCo(pddt)] (Y = –(CH 2) 3–), [CpCo(dpdt)] (Y = –CH 2C(CH 2)CH 2–), [CpCo(bddt)] (Y = –(CH 2) 4–), [CpCo(dtdt)] (Y = –CH 2SCH 2–) and [CpCo(poddt)] (Y = –CH 2C(O)CH 2–) crystallized in all isostructural with the corresponding paramagnetic [CpNi(dithiolene)] complexes, but [CpCo(dmid)] (Y = C O), [CpCo(dddt)] (Y = –(CH 2) 2–) and [CpCo(F 2pddt)] (Y = –CH 2CF 2CH 2–) crystallized in non-isostructural with them. These molecules are associated with intermolecular short S⋯S contacts in the crystals. [CpCo(F 2pddt)] 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)] complexes (near-IR).