Synthesis and preparative HPLC-separation of heteronuclear oligometallocenes. Isolation of cations of rhodocenylferrocene, 1,1′-dirhodocenylferrocene, and 1-cobaltocenyl-, 1′-rhodocenylferrocene
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Summary
New members of mixed metal termetallocenes, 1,1′-dirhodoceniumylferroceneII, and 1-cobaltoceniumyl,1′-rhodoceniumylferroceneIII, were prepared by statistical nucleophilic attack of dilithioferrocene on equimolar amounts of cobaltocenium and rhodocenium hexafluorophosphate. Subsequent hydride abstraction with tritylium hexafluorophosphate yielded the respective termetallocene dications. Also a new bimetallocene monocation, ferrocenylrhodoceniumI, a byproduct formed from partial protonation of dilithioferrocene, was identified. The new compounds were separated from undesired metallocenes, starting metallocenes, and byproducts by means of preparative HPLC. A reversed phase system was established which is sufficiently tuneable in selectivity to separate the different metallocene cationic species. The isolated compounds were characterized by NMR, IR, and ICP. through the delocalized system of π-electrons [2]. The realisation of threefold mixed metal termetallocenes allows direct comparison of the influence of different substituents on a bridging metallocene, which is of special interest for extreme push-pull aromatic compounds like neutral metallocenes substituted with valence trapped metallocene cations.
Key Words
Preparative column liquid chromatography Metallocene salt isolation Heteronuclear termetallocenesPreview
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References
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