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⁷⁷Se NMR spectroscopy as a sensitive probe for Hammett σ constants
Anne Sørensen1, Brian Rasmussen1, Michael Pittelkow1
1Department of Chemistry, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
The Journal of Organic Chemistry
|April 4, 2015
Summary
Nuclear Magnetic Resonance (NMR) spectroscopy, including selenium-77 NMR, effectively analyzes chemical structure correlations. This study demonstrates its utility for substituted aryl selenocarbamates, revealing linear relationships with electronic properties.
Area of Science:
- Organic Chemistry
- Spectroscopy
- Computational Chemistry
Background:
- Nuclear Magnetic Resonance (NMR) spectroscopy is a powerful technique for elucidating molecular structures.
- Selenium-77 (77Se) NMR spectroscopy offers unique insights into selenium-containing compounds.
- Correlation analysis in organic chemistry often relies on spectroscopic data and electronic substituent effects.
Purpose of the Study:
- To investigate the utility of combined (1)H, (13)C, and (77)Se NMR spectroscopy for correlation analysis.
- To explore the relationship between NMR parameters and electronic properties of substituted O-aryl and Se-aryl selenocarbamates.
- To validate the application of (77)Se NMR spectroscopy in structure-property relationship studies.
Main Methods:
- Synthesis and characterization of O-aryl selenocarbamates [ArOC(Se)N(CH3)2] and Se-aryl selenocarbamates [ArSeC(O)N(CH3)2].
- Acquisition and analysis of (1)H, (13)C, and (77)Se NMR spectra.
- Determination of chemical shifts and (13)C-(77)Se coupling constants.
- Application of linear free energy relationships using Hammett's σ(p) and σ(p)(-) constants.
Main Results:
- Observed linear free energy relationships between NMR chemical shifts/coupling constants and Hammett constants for both O-aryl and Se-aryl selenocarbamates.
- Identified specific (13)C and (77)Se chemical shifts and (13)C-(77)Se coupling constants that correlate with substituent effects.
- Demonstrated strong internal consistency in the (77)Se NMR data, supporting its reliability for correlation analysis.
Conclusions:
- Combined NMR techniques, particularly (77)Se NMR, are sensitive tools for correlation analysis in organic chemistry.
- (77)Se NMR spectroscopy provides valuable data for understanding electronic effects in substituted aryl selenocarbamates.
- The observed linear correlations validate the use of NMR spectroscopy for predicting and analyzing substituent effects in these selenium-containing compounds.
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