Pyridones cations, structure

Hydroxy pyridine 1-oxides are also tautomeric the 4-isomer exists in about equal amounts of forms (783) and (784). 4-Hydroxy-pyrones and -pyridones exhibit a different type of tautomerism the a-one (e.g. 785) structure is favored relative to the y-one structure. (3-Hydroxy-4-pyrones such as kojic acid (786) show phenolic properties (CHEC 3.28, Scheme 30). a- and 3-Hydroxy cations (e.g. 787) are the conjugate acids of pyridones and pyrones and are considered in the next section. 

In 1964, the syntheses of the cationic tris[l-oxopyridin-2-olato(l-)]-silicon(IV) complexes 39 1 were claimed, " based on elemental analyses and ESCA data for 39. " Very recently, we succeeded in synthesizing and characterizing the related complexes 42-44 (synthesis of 42 Scheme 24.5). Compound 42 C5H5NO2 (C5H5NO2 = l-hydroxy-2-pyridone or 2-hydroxy-pyridine 7V-oxide) was structurally characterized by single-crystal X-ray diffraction the Si coordination polyhedron was found to be a distorted octahedron. 

Batts, B.D., and E. Spiner. 1969. Vibration-spectral and structural comparison of the 4-aminopyridine cation with the 4-hydroxypyridinium ion and 4-pyridone. The protio parent ions, N- and C-deuterated, and N-methylated ions. Relevant N.M.R. spectral... 

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