Formation, Isolation, and Spectroscopic Properties of Some Isomers of C60H38, C60H40, C60H42, and C60H44 − Analysis of the Effect of the Different Shapes of Various Helium-Containing Hydrogenated Fullerenes on Their 3He Chemical Shifts

• Published in: European journal of organic chemistry 2003-11, Vol.2003 (21), p.4140-4145
• Main Authors: Peera, Asghar, Saini, Rajesh K., Alemany, Lawrence B., Billups, W. Edward, Saunders, Martin, Khong, Anthony, Syamala, M. S., Cross, R. James
• Format: Article
• Language: English
• Subjects: Fullerenes; Helium; Hydrogenations; NMR spectroscopy
• ISSN: 1434-193X; 1099-0690
• DOI: 10.1002/ejoc.200300350

A complex mixture of C60H38 to C60H44 has been prepared by a much milder procedure (Benkeser reduction) than the hydrogenation procedures that have frequently been used to produce such highly hydrogenated derivatives of C60. 1H and 13C NMR spectra of fractions isolated by HPLC showed that more highly hydrogenated fullerenes exhibited signals that were shifted upfield. The opposite trend appears to hold in 3He NMR spectra of the corresponding endohedral helium compounds. The changes in the 1H, 13C, and 3He chemical shifts are reasonable for fullerenes hydrogenated to different extents. In particular, previously reported substantial changes in the shapes of the various hydrogenated fullerenes can reasonably account for the interesting trends apparent both in the 3He chemical shifts of He@C60Hx (x = 0−44) and in the HPLC retention times of the corresponding non‐helium‐containing species. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)