Sodium fullerides

Mesoporous tantalum oxide-sodium fulleride composites were characterised by the use of solid-state 13C and 23Na NMR spectra.135... 

To make the reactive fulleride compound KeCeo in the Fe-Ceo synthesis, fullerenes and a slight excess of potassium were sealed in a glass tube under vacuum and heated for approximately four days at 250 °C. Both solid-state NMR and Raman spectroscopy were employed to determine that the KeCeo compound was in fact synthesized. The KeCeo product was then reacted in an inert atmosphere with cyclopentadienyl-iron-dicarbonyl-iodide (CpFe(CO)2l) in tetrahydrofuran (THF) to form the complex. The recovered product was dried in an inert atmosphere. Manipulations of air-sensitive materials were carried out in a glove box or using standard Schlenk techniques. THF was distilled just prior to use from sodium benzophenone ketyl. Ceo was obtained from Aldrich, and CpFeCCOjol was obtained from Strew. 

Ta92b K. Tanigsdci ei al, Superconductivity in Sodium- and Lithium-Containing Alkali-Metal Fullerides, Nature 356, 419-421... 

E24.28 In Na2C o, all of the tetrahedral holes are filled with sodium cations within the close-packed array of fulleride anions—in other words, it has an antifluorite structure (see Section 3.9(a)). In NajC >, all of the tetrahedral holes and all of the octahedral holes are filled with sodium cations within the fee lattice of fulleride anions. 

Two separate samples of NasCgo were prepared by direct reaction of Ceo with sodium metal vapor, and subjected to different annealing times of 10 16 days. C and Na solid-state NMR, along with elemental analysis, powder XRD and Raman spectroscopy, were used to characterise both samples. Na and C solid-state NMR spectra of the two samples are significantly different, suggesting a relationship between annealing times and the final structure of the alkali fulleride. Na VTMAS NMR experiments reveal the existence of two or three distinct Na species and reversible temperature-dependent diffusion of sodium ions between octahedral and tetrahedral interstitial sites. C MAS NMR experiments are used to identify resonances corresponding to free Ceo and fulleride species. ... 

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