Chemistry and Physics Faculty Proceedings, Presentations, Speeches, Lectures

Title

C-H Activation and CO2 Insertion Reactivity of Unsolvated Lanthanide Alkyl and Aryl Metallocenes

Event Name/Location

227th National Meeting of the American Chemical Society: Organometallic Metallocenes / Anaheim, California

Document Type

Lecture

Publication Date

3-2004

Abstract

Among the most reactive types of organolanthanide complexes are the unsolvated decamethylmetallocene alkyls, [(C5Me5)2LnR]n. These complexes are difficult to isolate since they typically activate C-H bonds in arene and ethereal solvents. Previous attempts to make these complexes have involved difficult multi-step syntheses. Recently, it has been shown that the readily prepared metallocene cations, [(C5Me5)2Ln][µ-Ph2BPh2], are convenient precursors to unsolvated lanthanide methyl metallocenes, such as [(C5Me5)2LnMe]n (Ln=Sm, Lu), both of which crystallize with asymmetric structures. This has allowed the reaction chemistry of [(C5Me5)2SmMe]3 to be investigated for the first time. This unsolvated methyl complex metallates toluene to give a material with spectral characteristics appropriate for [(C5Me5)2SmCH2Ph]n but derivatization with CO2 gives a mixture of benzyl and meta tolyl carboxylates. Solid state data on the [(C5Me5)2SmMe]3/toluene product shows a disordered structure with two metallocenes per tolyl unit. To obtain more information on these basic C-H activation and CO2 insertion reactions, the reactivity of related [(C5Me5)2SmR]n complexes was examined. Synthesis of the [(C5Me5)2SmR]n complexes by both C-H activation starting with [(C5Me5)2SmMe]3 and ionic metathesis starting with [(C5Me5)2Sm][µ-Ph2BPh2] were examined. This manifold of inter-related unsolvated alkyl and aryl metallocene reaction chemistry will be described.

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