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Nossal J, Saini RK, Sadana AK, et al. Formation, isolation, spectroscopic properties, and calculated properties of some isomers of C(60)H(36). J Am Chem Soc. 2001;123(35):8482-95doi: 10.1021/ja0108180.
Nossal, J., Saini, R. K., Sadana, A. K., Bettinger, H. F., Alemany, L. B., Scuseria, G. E., Billups, W. E., Saunders, M., Khong, A., & Weisemann, R. (2001). Formation, isolation, spectroscopic properties, and calculated properties of some isomers of C(60)H(36). Journal of the American Chemical Society, 123(35), 8482-95. https://doi.org/10.1021/ja0108180
Nossal, J, et al. "Formation, isolation, spectroscopic properties, and calculated properties of some isomers of C(60)H(36)." Journal of the American Chemical Society vol. 123,35 (2001): 8482-95. doi: https://doi.org/10.1021/ja0108180
Nossal J, Saini RK, Sadana AK, Bettinger HF, Alemany LB, Scuseria GE, Billups WE, Saunders M, Khong A, Weisemann R. Formation, isolation, spectroscopic properties, and calculated properties of some isomers of C(60)H(36). J Am Chem Soc. 2001 Sep 05;123(35):8482-95. doi: 10.1021/ja0108180. PMID: 11525655.
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J Am Chem Soc. 2001 Sep 05;123(35):8482-95. doi: 10.1021/ja0108180.

Formation, isolation, spectroscopic properties, and calculated properties of some isomers of C(60)H(36).

Journal of the American Chemical Society

J Nossal, R K Saini, A K Sadana, H F Bettinger, L B Alemany, G E Scuseria, W E Billups, M Saunders, A Khong, R Weisemann

Affiliations

  1. Department of Chemistry, Rice University, Houston, TX 77005, USA.

PMID: 11525655 DOI: 10.1021/ja0108180

Abstract

Isomers of C(60)H(36) and He@C(60)H(36) have been synthesized by the Birch or dihydroanthracene reduction of C(60) and isolated by preparative high-pressure liquid chromatography. (3)He, (13)C, and (1)H NMR spectroscopic properties were then determined. A comparison of experimental chemical shifts against those computed using density functional theory (B3LYP) with polarized triple- and double-zeta basis sets for He and C,H, respectively, allowed provisional assignment of structure for several isomers to be made. Theoretical calculations have also been carried out to identify low-energy structures. The transfer hydrogenation method using dihydroanthracene gives a major C(60)H(36) isomer and a minor C(60)H(36) isomer with C(3) symmetry as determined by the (13)C NMR spectrum of C(60)H(36) and the (3)He NMR spectrum of the corresponding sample of (3)He@C(60)H(36). In view of the HPLC retention times and the (3)He chemical shifts observed for the Birch and dihydroanthracene reduction products, the two isomers generated by the latter procedure can be only minor isomers of the Birch reduction. A significant energy barrier apparently exists in the dihydroanthracene reduction of C(60) for the conversion of the C(3) and C(1) symmetry isomers of C(60)H(36) to the T symmetry isomer previously predicted by many calculations to be among the most stable C(60)H(36) isomers. Many of the (1)H NMR signals exhibited by C(60)H(36) (and C(60)H(18), previously reported) are unusually deshielded compared to "ordinary" organic compounds, presumably because the unusual structures of C(60)H(36) and C(60)H(18) result in chemical shift tensors with one or more unusual principal values. Calculations clearly show a relationship between exceptionally deshielded protons beta to a benzene ring in C(60)H(18) and C(60)H(36) and relatively long C-C bonds associated with these protons. The additional information obtained from 1D and 2D (1)H NMR spectra obtained at ultrahigh field strengths (up to 900 MHz) will serve as a critical test of chemical shifts to be obtained from future calculations on different C(60)H(36) isomers.

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