Characteristic infra-red absorption frequencies of organophosphorus compounds—VI. Bonds between phosphorus and nitrogen

Abstract

In cyclic compounds, and others containing NPN groups, ν_PN is assigned to the region 1170–1438 cm⁻¹. In compounds in which resonance hybrids involving PN appear unlikely ν_PN is found in the range 1325–1400 cm⁻¹. It is suggested that this upper limit would be exceeded in compounds of this type containing fluorine substituents.

The literature assignments for PN bonds are discussed and it is suggested that this bond is best identified by indirect correlations. Such correlations are described for PNH₂, PNHR, PNR₂,

, PNC and PNP groups. As a result of these correlations it is concluded that ν_PN should be assigned to the range 873–1053 cm⁻¹.