Essential Factors for Control of the Equilibrium in the Reversible Rearrangement of M3N@Ih‐C80 Fulleropyrrolidines: Exohedral Functional Groups versus Endohedral Metal Clusters. Issue 43 (5th September 2014)

• Record Type: Journal Article
• Authors: Aroua, Safwan; Garcia‐Borràs, Marc; Osuna, Sílvia; Yamakoshi, Yoko
• Is Part Of: Chemistry. Volume 20:Issue 43(2014)
• Page Start: 14032
• Page End: 14039
• Publication Date: 2014-09-05
• Subjects: DFT calculations -- fullerenes -- isomerization -- nitrogen heterocycles -- Prato reaction; Chemistry -- Periodicals; 540
• DOI: 10.1002/chem.201403743
• Languages: English
• ISSNs: 0947-6539

Abstract

Abstract: The effects of exohedral moieties and endohedral metal clusters on the isomerization of M3 N@ Ih ‐ C80 products from the Prato reaction through [1, 5]‐sigmatropic rearrangement were systematically investigated by using three types of fulleropyrrolidine derivatives and four different endohedral metal clusters. As a result, all types of derivatives provided the same ratios of the isomers for a given trimetallic nitride template (TNT) as the thermodynamic products, thus indicating that the size of the endohedral metal clusters inside C80 was the single essential factor in determining the equilibrium between the [6, 6]‐isomer (kinetic product) and the [5, 6]‐isomer. In all the derivatives, the [6, 6]‐ and [5, 6]‐Prato adducts with larger metal clusters, such as Y3 N and Gd3 N, were equally stable, which is in good agreement with DFT calculations. The reaction rate of the rearrangement was dependent on both the substituent of exohedral functional groups and the endohedral metal‐cluster size. Further DFT calculations and 13 C NMR spectroscopic studies were employed to rationalize the equilibrium in the rearrangement between the [6, 6]‐ and [5, 6]‐fulleropyrrolidines. Abstract : Metal size and dipole effect! The effects of the size of the metal cluster inside the carbon cage and dipole held by the pyrrolidine nitrogen atom on the regioisomerization of M3 N@C80 adducts were investigated (see figure). Interestingly, the metal‐cluster size determines the thermodynamically more‐stable regioisomer, whereas the dipole and metal‐cluster size controls the rate of the isomerization.