Synthesis and characterization of bis(ferrocenylcarboxylato)telluranes

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From: Canadian Journal of Chemistry(Vol. 85, Issue 7-8)
Publisher: NRC Research Press
Document Type: Article
Length: 3,824 words
Lexile Measure: 1540L

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Abstract: A convenient route to the synthesis of the first bis(ferrocenyl carboxylato) telluranes has been developed. Reactions of 1,1,2,3,4,5,6-heptahydro-1,1-(dihydroxo)tellurane and 1,1,2,3,4,5-hexahydro-1,1-(dihydroxo)tellurophene with ferrocene carboxylic acid give 1,1,2,3,4,5,6-heptahydro-1,1-bis(ferrocenyl carboxylato)tellurane (3) and 1,1,2,3,4,5,-hexahydro-1,1-bis(ferrocenyl carboxylato)tellurophene (5), respectively. The X-ray structure of 3 shows that it contains a tellurium heterocycle (C5H1OTe), present in a chair conformation, sandwiched between two ferrocene units with carboxylate groups acting as spacers. Compound 3 also exhibits modest second harmonic generation (SHG) efficiency. The electrochemical studies of 3 and 5 through cyclic voltammetry show only one oxidation wave, indicating the presence of independent redox centers leading to reversible single-step two-electron redox systems.

Key words: tellurane, ferrocenylcarboxylate, SHG efficiency, electrochemistry.

Resume: On a mis an point une methode pratique de synthese des premiers bis(ferrocenylcarboxylato)telluranes. La reaction du 1,1,2,3,4,5,6-heptahydro-1,1-(dihydroxo)tellurane et du 1,1,2,3,4,5-hexahydro-1,1-(dihydroxo)tellurophene avec l'acide carboxylique du ferrocene conduit respectivement a la formation de 1,1,2,3,4,5,6-heptahydro-1, 1-bis(ferrocenylcarboxylato)tellurane (3) et de 1,1,2,3,4,5-hexahydro-1,1-bis(ferrocenylcarboxylato)tellurophene (5). La structure du compose 3 telle que determinee par diffraction des rayons X montre qu'elle contient un heterocycle de tellure (C5HIOTe) qui est present sous une conformation chaise et qui est pris en sandwich entre deux unites de ferrocene auxquelles il est retenu par des groupes carboxylates agissant comme cales. Le compose 3 possede aussi une faible efficacite dans la generation de la deuxieme harmonique (GDH). Les etudes electrochimiques des composes 3 et 5 realisees par le biais de voltamperometrie cyclique ne presentent qu'une seule vague d'oxydation, ce qui indique la presence de centres redox independants qui conduisent a des systemes redox a deux electrons impliquant une seule etape reversible.

Mots-cles: tellurane, ferrocenylcarboxylate, efficacite dans la generation de la deuxieme harmonique, electrochimie.

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Introduction

Bridged ferrocenes containing main group (13-16) (p-block) elements are known and generally exist as polymers or oligomers (1-9). Ferrocene derivatives containing boron bridges have been synthesized by the reaction of dilithiated ferrocene and bis(dimethylboryl) ferrocene or bis(trimethylstannyl) ferrocene with PhBC12 (1, 2). A multinuclear ferrocene derivative with aluminium substitution has been synthesized by the reaction between dilithiated ferrocene with Al[Et.sub.2]C1 (3). The reaction of 1,1'-bis(trichlorostannyl) ferrocene with [Me.sub.3]Ga results in the formation of 1,1'-digallyl ferrocene (4). Ring-opening polymerization (ROP) of main group element bridged [1]- and [2]-ferrocenophanes by thermal or anionic methods results in high molecular weight polymers containing ferrocene groups alternating with either boron, carbon, silicon, germanium, tin, or phosphorous atoms (5-7). A hexa-ferrocene unit on a tin-oxygen cluster has been synthesized by the reaction of n-butylstannonic acid with ferrocene monocarboxylic acid (8). A chalcogen (sulphur) bridged polymer has been synthesized by the reaction of trithia ferrocenophanes with [Bu.sub.3]P (9). The interactions between main group elements and transition elements of the periodic table lead to useful precursors for ceramics, electronic materials, and catalysts (10, 11); if the transition metal containing entities are metallocenes (particularly ferrocenes), such combinations exhibit novel electrical, optical, chemical, and magnetic characteristics (12, 13). These include redox active materials for modification of electrodes (14) or materials that can function as multi-electron redox systems (15), biosensors (16a, 16b), or variable refractive index...

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Gale Document Number: GALE|A167778892