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Structural Chemistry

, Volume 19, Issue 4, pp 637–644 | Cite as

Conformational analysis of N-isopropylbenzohydroxamic acids: crystal structure, DFT, and NMR studies

  • Witold PrzychodzeńEmail author
  • Jarosław Chojnacki
Original Research

Abstract

X-ray crystal structure determinations together with density functional theory (DFT) calculations in vacuo and NMR studies in solution have been carried out for 4-MeOC6H4CONPriOH 2a and 3,5-(NO2)2C6H3CONPriOH 2b. The results were compared with that for the respective N-methyl benzohydroxamic acids. For crystal structures as well as for DFT-optimized geometries of 2 (both isomers) in vacuo, the effect of substituents in aromatic ring manifested by changing of charges is inconspicuous. Studies of potential energy surfaces showed that libration barrier around ω 1 = 0° is low enough to make electron conjugation feasible, and that for 2b rotation barrier around C(O)N bond is higher by 6 kcal/mol and additionally, that rotation around N–C bond is hindered. A careful analysis of low-temperature 1H NMR spectra confirmed the greater stability of Z-2a, the greater rigidity of E-2b and the influence of solvent on both isomers population. Despite solvent-dependent conformational alteration, both 2a and 2b crystallize exclusively as E isomers from ethyl acetate solution. Correlations of absolute 1H, 13C, and 15N shielding calculations with experimental data were also analyzed.

Keywords

Hydroxamic acids X-ray structure DFT calculations Substituent effects Conformations Absolute nuclear shieldings 

Notes

Acknowledgments

We thank Dr. P. Sowiński for measurement of the NMR spectra. The studies were financially supported in part by the Polish Ministry of Science and Informatisation, grant No. 1T09A 07830.

Supplementary material

11224_2008_9338_MOESM1_ESM.pdf (640 kb)
(PDF 640 kb)

References

  1. 1.
    Miller MJ (1989) Chem Rev 89:1563. doi: 10.1021/cr00097a011 CrossRefGoogle Scholar
  2. 2.
    Marmion CJ, Griffith D, Nolan KB (2004) Eur J Inorg Chem 3003. doi: 10.1002/ejic.200400221
  3. 3.
    Brown DA, Coogan RA, Fitzpatrick NJ, Glass WK, Abukshima DE, Shiels L et al (1996) J Chem Soc Perkin Trans 2:2673. doi: 10.1039/p29960002673 Google Scholar
  4. 4.
    Kalinin VN, Yurchenko VM (1982) Russ J Org Chem 48:1455Google Scholar
  5. 5.
    El Yazal J, Pang Y-P (1999) J Phys Chem A 103:8346. doi: 10.1021/jp992203j CrossRefGoogle Scholar
  6. 6.
    Niño A, Muñoz-Caro C, Senent ML (2000) J Mol Struct Theochem 530:291. doi: 10.1016/S0166-1280(00)00342-0 Google Scholar
  7. 7.
    Allen FH (2002) Acta Crystallogr B58:380Google Scholar
  8. 8.
    Yamasaki R, Tanatani A, Azumaya I, Masu H, Yamaguchi K, Kagechika H (2006) Cryst Growth Des 6:2007. doi: 10.1021/cg060151z CrossRefGoogle Scholar
  9. 9.
    Przychodzeń W (2005) Eur J Org Chem 10:2002Google Scholar
  10. 10.
    Przychodzeń W (2006) Heteroat Chem 17:676. doi: 10.1002/hc.20259 CrossRefGoogle Scholar
  11. 11.
    Przychodzeń W, Doszczak L, Rachon J (2005) Magn Reson Chem 43:27. doi: 10.1002/mrc.1497 CrossRefGoogle Scholar
  12. 12.
    Frisch MJ, Trucks GW, Schlegel HB, Scuseria GE, Robb MA, Cheeseman JR et al (2004) Gaussian 03, Revision D.01. Gaussian Inc, WallingfordGoogle Scholar
  13. 13.
    Vargas R, Garza J, Dixon D, Hay BP (2001) J Phys Chem A 105:774. doi: 10.1021/jp003340f CrossRefGoogle Scholar
  14. 14.
    Hrobárik P, Horváth B, Sigmundová I, Zahradnik P, Malkina OL (2007) Magn Reson Chem 45:942. doi: 10.1002/mrc.2074 CrossRefGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2008

Authors and Affiliations

  1. 1.Faculty of ChemistryGdańsk University of TechnologyGdanskPoland

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