MULTINUCLEAR FERROCENE DERIVATIVES WITH CHALCOGEN BRIDGES

Oligonuclear ferrocene derivatives containing either sulfur or disulfur bridges were obtained by three methods **: 1.) The reaction of 1,1'-dilithioferrocene, fcLi2, with diferrocenyldisulfane, Fc-SS-Fc (1a), can be used to prepare trinuclear 1,1'-bis(ferrocenylthiolato)ferrocene, Fc-S-fc-S-Fc (9a); the selenium-and tellurium-bridged complexes Fc-E-fc-E-Fc (E = Se (9b), Te (9c)) are accessible in an analogous manner. 2.) 1,2,3-Trithia[3]ferrocenophane, fc(S3), reacts with organolithium compounds, RLi, to give (after air oxidation) bis(1'-organylthiolato-ferrocenyl)disulfanes, RS-fc-SS-fc-SR (R = (n)butyl (11a) and phenyl (12a)); in the case of lithioferrocene (R = Fc) a tetranuclear product, FcS-fc-SS-fc-SFc (13a), is formed. 3.) Radical-initiated (AIBN) reactions of 1,1'-ferrocenedithiol, fc(SH)2, often lead to oligonuclear ferrocene derivatives containing disulfur bridges. The AIBN induced reaction between fc(SH)2 and ferrocenethiol, FcSH, gives yellow products the majority of which are insoluble in organic solvents. The fraction soluble in hexane/ethylacetate (10:1) contained small amounts of Fc-SS-Fc (1a) and Fc-SS-fc-SS-Fc (15a). The AIBN induced reaction of fc(SH)2 with norbornadiene (1:1) gives oligomers C7H9S-fc-S-[S-fc-S]n-2-S-fc-SC7H9 (16a) in which the chain consists of disulfur-bridged 1,1'-ferrocenylene units and the end groups are either 3-nortricyclyl or 5-exo-norborn-2-enyl substituents. Oligomers with a chain length of n = 2-12 were observed by gel permeation chromatography (GPC), the average number (nBAR) of ferrocene building blocks being close to nBAR = 3. The new compounds were identified by their EI mass spectra and characterized by their C-13 NMR spectra.