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Organometallic compounds

Samarium forms a cyclopentadienide Sm(C H) and its chloroderivatives Sm(C H) Cl and Sm(C H)Cl. They are prepared by reacting samarium trichloride with NaC H in tetrahydrofuran. Contrary to cyclopentadienides of most other lanthanides, in Sm(C H) some C H rings bridge each other by forming ring vertexes η or edges η toward another neighboring samarium, thus creating polymeric chains. The chloroderivative Sm(C H) Cl has a dimer structure, which is more accurately expressed as (η()−C H) Sm(−Cl) (η()−C H). There, the chlorine bridges can be replaced, for instance, by iodine, hydrogen or nitrogen atoms or by CN groups.

The (C H) ion in samarium cyclopentadienides can be replaced by the indenide (C H) or cyclooctatetraenide (C H) ring, resulting in Sm(C H) or KSm(η()−C H). The latter compound has a structure similar to uranocene. There is also a cyclopentadienide of divalent samarium, Sm(C H) a solid that sublimates at about 85 °C (185 °F). Contrary to ferrocene, the C H rings in Sm(C H) are not parallel but are tilted by 40°.

A metathesis reaction in tetrahydrofuran or ether gives alkyls and aryls of samarium:

Here R is a hydrocarbon group and Me = methyl.