Compounds containing a phosphorus–nitrogen double bond, i.e. derivatives of
H3P=NH and
HP=NH. A multiplicity of such bonds is present in various well-established chain, ring and cage compounds. E.g.
P04551-1.png
P04551-2.png
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1357 (https://doi.org/10.1351/pac199567081307)