Experimental evidence for the breakdown of the karplus relationship for 3J(13C, 1H) in 1H-C-C=13C systems

Teodor Parella, Francisco Sánchez-Ferrando, Albert Virgili

Research output: Contribution to journalArticleResearchpeer-review

12 Citations (Scopus)

Abstract

Vicinal 1H, 13C coupling constants were measured for rigid unsaturated 1H-C-C=13C molecular frameworks at natural abundance. As a general trend, an empirical range of 4.5-6.5 Hz is observed independent of the value of the dihedral angle between the CH bond and the plane of the double bond. Furthermore, through-bond and through-space substituent effects also influence the magnitude of the coupling constants in a similar way to that known for saturated systems. In summary, two different additive transmission mechanisms take part in these coupling paths depending on the orientation of the π-system with respect to the allylic bond. The experimental evidence presented demonstrates the breakdown of the Karplus rule in this particular structural fragment.
Original languageEnglish
Pages (from-to)30-34
JournalMagnetic Resonance in Chemistry
Volume35
Issue number1
DOIs
Publication statusPublished - 1 Jan 1997

Keywords

  • 1 H NMR
  • Allylic systems
  • Long-range proton-carbon coupling constants
  • NMR

Fingerprint Dive into the research topics of 'Experimental evidence for the breakdown of the karplus relationship for <sup>3</sup>J(<sup>13</sup>C, <sup>1</sup>H) in <sup>1</sup>H-C-C=<sup>13</sup>C systems'. Together they form a unique fingerprint.

  • Cite this