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¹³C NMR Study of Halogen Bonding of Haloarenes: Measurements of Solvent Effects and Theoretical Analysis
Journal of the American Chemical Society
  • Rainer Glaser, Missouri University of Science and Technology
  • Naijun Chen
  • Hong Wu
  • Nathan Knotts
  • Martin Kaupp
Abstract

Solvent effects on the NMR spectra of symmetrical (X = F (1), X = Cl (2), X = Br (3), X = I (4), X = NO2 (5), X = CN (6)) and unsymmetrical (X = I, Y = MeO (7), Y = PhO (8)) para-disubstituted acetophenone azines X-C6H4-CMe═N-N═CMe-C6H4-Y and of models X-C6H4-CMe═N-Z (X = I, Z = H (9), Z = NH2 (10)), 4-iodoacetophenone (11), and iodobenzene (12) were measured in CDCI3, DMSO, THF, pyridine, and benzene to address one intramolecular and one intermolecular issue. Solvent effects on the 13C NMR spectra are generally small, and this finding firmly establishes that the azine bridge indeed functions as a "conjugation stopper," an important design concept in our polar materials research. Since intermolecular halogen bonding of haloarenes do occur in polar organic crystalline materials, the NMR solution data pose the question as to whether the absence of solvent shifts indicates the absence of strong halogen bonding in solution. This question was studied by the theoretical analysis of the DMSO complexes of iodoarenes 4, 9-12, and of iodoacetylene. DFT and MP2 computations show iodine bonding, and characteristic structural and electronic features are described. The nonrelativistic complexation shifts and the change in the spin-orbit induced heavy atom effect of iodine compensate each other, and iodine bonding thus has no apparent effect on Ci in the iodoarenes. For iodides, complexation by DMSO occurs and may or may not manifest itself in the NMR spectra. The absence of complexation shifts in the NMR spectra of halides does not exclude the occurrence of halogen bonding in solution.

Department(s)
Chemistry
Sponsor(s)
University of Missouri Research Board
University of Missouri Research Council
National Institutes of Health (U.S.)
Comments
This work was supported by the UM Research Board, the MU Research Council, and the United States National Institutes of Health (GM61027).
Keywords and Phrases
  • Chemical Bonds,
  • Complexation,
  • Nuclear Magnetic Resonance Spectroscopy,
  • Organic Solvents,
  • Halogen Bonding,
  • Solvent Effects,
  • Aromatic Hydrocarbons,
  • 4 Iodoacetophenone,
  • Acetophenone Derivative,
  • Benzene,
  • Chloroform,
  • Dimethyl Sulfoxide,
  • Halide,
  • Halogenated Hydrocarbon,
  • Hydrazine,
  • Iodine Derivative,
  • Iodobenzene,
  • Polycyclic Aromatic Hydrocarbon,
  • Pyridine,
  • Solvent,
  • Unclassified Drug,
  • Carbon Nuclear Magnetic Resonance,
  • Complex Formation,
  • Crystal Structure,
  • Enthalpy,
  • Entropy,
  • Halogen Bond,
  • Proton Nuclear Magnetic Resonance,
  • Theoretical Study,
  • Vibration
Document Type
Article - Journal
Document Version
Citation
File Type
text
Language(s)
English
Rights
© 2004 American Chemical Society (ACS), All rights reserved.
Publication Date
4-1-2004
Publication Date
01 Apr 2004
PubMed ID
15053631
Disciplines
Citation Information
Rainer Glaser, Naijun Chen, Hong Wu, Nathan Knotts, et al.. "¹³C NMR Study of Halogen Bonding of Haloarenes: Measurements of Solvent Effects and Theoretical Analysis" Journal of the American Chemical Society Vol. 126 Iss. 13 (2004) p. 4412 - 4419 ISSN: 0002-7863; 1520-5126
Available at: http://works.bepress.com/rainer-glaser/13/