EPR Spectroelectrochemical Experiment

The choice and concentration of electrolyte can be important in EPR spectroelectrochemical experiments. Usually, it is assumed that the electrolyte, added to lower the resistance of the solvent and hence aid the electrogeneration process, is inert. This is not always the case, particularly, if the unpaired electron occupies an orbital that is localised on one part of the redox-active molecule. Such a situation will lead to a highly polarised redox product that 

Experimental and simulated EPR spectra of [CgH5N02] generated in situ at -l.OV Vi. Ag/AgCl at 233 K, recorded at 233 K in CHjCN (no electrolyte). 

EPR hyperfine coupling constants for (NO2-C6H5) in CH3CN for various electrolyte cations (0.1 M). 

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In general, EPR spectroelectrochemical experiments are usually conducted on species that are diamagnetic in their starting redox state and hence the EPR signal appears on electrogeneration. Transition-metal coordination compounds often show rich electrochemical behaviour and it is from this class of compounds that many of the examples considered here are taken. 

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