isocyanides

https://doi.org/10.1351/goldbook.I03270
The isomerHN+≡C of hydrocyanic acid, HC≡N, and its hydrocarbyl derivatives RNC (RN+≡C).
Source:
PAC, 1995, 67, 1307. 'Glossary of class names of organic compounds and reactivity intermediates based on structure (IUPAC Recommendations 1995)' on page 1344 (https://doi.org/10.1351/pac199567081307)