Synthetic and Electrochemical Studies on 1,1‘-Dithia-Substituted Derivatives of Ferrocene and Structure of 1,3-Dithia[3]ferrocenophane [Fe(C₅H₄S)₂CH₂]

The bimetallic complexes fc(μ₂-S)₂TiCp₂ (1, fc = 1,1‘-ferrocenyl, Cp = cyclopentadienyl) and fc(μ₂-S₂)(μ₂-S)TiCp₂ (2) were synthesized by reaction of fc(SH)₂ with Cp₂TiCl₂, and from fcS₃ and Cp₂Ti(CO)₂, respectively. The novel tetrasulfane fcS₄ was obtained from 2 and SCl₂. 1,3-Dithia[3]ferrocenophane fcS₂CH₂ was obtained from fc(SH)₂ and CH₂Cl₂ in the presence of Cp₂TiCl₂ and KOH. The molecular and crystal structure of fcS₂CH₂ was determined by X-ray crystallography; the molecular symmetry is C_s. Electrochemical studies on the recently prepared ferrocenophanes fcS₂-1-SO, fcS₂-1-SO₂, and fcS₂-2-SO show that, with respect to fcS₃, the progressive oxidation of the trisulfane bridge makes more and more difficult the fc/fc⁺ oxidation, whereas insertion of a Cp₂Ti fragment exerts the opposite effect.