Electron spin resonance investigation of carbon-13 hyperfine interactions in nitrobenzene anion radical |
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Authors: | Grace L Swartz Wilson M Gulick Jr |
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Institution: | Department of Chemistry , The Florida State University , Tallahassee, Florida, 32306 |
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Abstract: | Synthesis of carbon-13 enriched nitrobenzene which contains 22·5 mole per cent of nitrobenzene-1-13C and an equal amount of nitrobenzene-4-13C has been accomplished. We report the carbon-13 hyperfine interactions in the corresponding anion radicals in a variety of solvent media. In hexamethylphosphoramide a C1 = -7·05 gauss and a C4 = 6·14 gauss. These couplings change to -9·03 gauss and 5·31 gauss, respectively, when the solvent medium is dimethylformamide containing 0·598 mole fraction of water. The solvent dependence of a C1 is consistent with the radical remaining planar as opposed to adopting a pyramidal conformation at the nitrogen when hydrogen bonds form between the radical anion and protic solvents. Data reported here provide an experimental means to estimate the spin density distribution in nitrobenzene anion. |
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