PROTONATION OF TRIETHYL (2-PYRIDYLIMIDO)PHOSPHATES

Protonation of triethyl (2-pyridylimido)phosphates has been studied by potentiometric titration in nitromethane, IR and NMR spectroscopy, an d X-ray structure analysis. The substances studied are protonated in o ne step at the N-atom of the pyridine ring. The protonated cations may be represented, according to the X-ray data, as a resonance of two st ructures: pyridinium and pyridoniminium; the contribution of the latte r probably being considerable. Changes in spectral parameters of POEt groups upon protonation of pyridylimidophosphates (PIP) have been note d.