Probes of Nonreactive Environment. IV. 1-Methyl-4-Cyanoformylpyridinium Oximate

摘要

The compound 1-methyl-4-cyanoformylpyridinium oximate (CPO) possesses two electronic absorption bands, which are measures of solvent polarity. These transitions are attributed to an intramolecular charge-transfer from oximate oxygen to the pyridinium ring (n to pi*) and vanish on protonation, metal complexation, or chemical reaction of the oxygen. The solubility, spectral solvent dependence, and zinc and cobalt metal complexes of CPO are described. An outline is given of the factors affecting the choice of CPO as a reagent for probing environment in solution. (Author)