Synthesis and reactivity of 1-chloro-2-methylthio-ferrocene and 1,1′-dichloro-2,2′-bis(methylthio)ferrocene. Molecular structure of 1-chloro-2,5-bis(methylthio)ferrocene

• Stepwise lithiation of CpFe(C5H4Cl) and addition of MeSSMe gives CpFe[C5H4−nCl(SMe)n] (n = 1; 2).
• The X-ray structure determination of 3 proves the 1, 2, 5 regiochemistry.
• (C5H4Cl)2Fe reacts with BuLi/TMEDA followed by MeSSMe to give [C5H3Cl(SMe)]2Fe (4).
• From 4 and BuLi followed by MeSSMe [C5H2Cl(SMe)2]2Fe can be obtained.

Lithiation of chloroferrocene (1a) with n-butyl lithium or lithium tetramethylpiperidinide (LiTMP) followed by addition of dimethyldisulfide gives 1-chloro-2-methylthioferrocene (2). Renewed treatment of 2 with LiTMP and MeSSMe yields 1-chloro-2,5-bis(methylthio)ferrocene (3), the structure of which was determined by X-ray diffraction. The reaction of 1,1′-dichloroferrocene (1b) with n-butyl lithium in the presence of TMEDA followed by addition of MeSSMe gives 1,1′-dichloro-2,2′-bis(methylthio)ferrocene as a diastereomeric 1:2 mixture of the meso and d,l form.

Lithiation of Monochloro- and 1,1′-dichloroferrocene followed by treatment with MeSSMe gives [C5H3Cl(SMe)]Fe[C5H5] and [C5H3Cl(SMe)]2Fe, respectively. Repeating the lithiation–methylthiolation sequence yields [C5H2Cl(SMe)2]Fe[C5H5], [C5H2Cl(SMe)2]2Fe and [C5H2Cl(SMe)2]Fe[C5H3Cl(SMe)] respectively. The molecular structure of [C5H2Cl(SMe)2]Fe[C5H5], determined by X-ray diffraction, shows the selective ortho-dilithiation of the chloroferrocene.Figure optionsDownload as PowerPoint slide