77Se NMR Spectroscopy As a Sensitive Probe for Hammett σ Constants

Herein we showcase the use of a combination of (1)H, (13)C, and (77)Se NMR spectroscopy as a sensitive tool for correlation analysis. A series of substituted O-aryl selenocarbamates [ArOC(Se)N(CH3)2] and Se-aryl selenocarbamates [ArSeC(O)N(CH3)2] have been investigated by means of (1)H, (13)C, and (77)Se NMR spectroscopy. We have determined the (1)H, (13)C, and (77)Se chemical shift values as well as both one- and two-bond heteronuclear (13)C-(77)Se coupling constants, and the changes in both the chemical shift values and the coupling constants were found to obey linear free energy relationships with Hammett's σ(p) and σ(p)(-) constants. For the eight studied O-aryl selenocarbamates, we observe linear free energy correlations with two of the (13)C and (77)Se chemical shift values and as well as one (13)C-(77)Se coupling constant. With the five examples of Se-aryl selenocarbamates, linear correlations are observed with three different (13)C-(77)Se coupling constants. The strong internal consistency validates the use of (77)Se NMR spectroscopy for correlation analysis.