VARIATION OF MU-NH FREQUENCY OF SOME SPIROPHOSPHORANES IN SOLVENTS - EVALUATION OF P(V)-NH GROUP ACIDITY IN THESE COMPOUNDS

A spectroscopical study of N-H bond in spirophosphoranes containing one or two such groups had been made. The value of 2Δν1-2 = 2ν0-1 - ν0-2 (CCl4 solution) give information on the anharmonicity of N-H stretching vibration. The frequency of the fundamental N-H stretching transition has been measured in several solvents and compared with the νN-H frequency of pyrrol in the same solvents. The N-H group in these compounds seem to be analogous to the same group in pyrrol. This can be interpreted as a result of sp2 hybridization of the nitrogen atom and a strong conjugation of the p orbital of the latter with a vacant d orbital of phosphorus atom. © 1969.