isocyanides

https://doi.org/10.1351/goldbook.I03270

The isomer HN⁺≡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)