The neutral species
HC…
and its derivatives formed by substitution in which a univalent carbon atom is covalently
bonded to one group and also bears three nonbonding electrons. (This term carries
no implication about spin-pairing).
Source:
PAC, 1995, 67, 1307
(Glossary of class names of organic compounds and reactivity intermediates based on
structure (IUPAC Recommendations 1995))
on page 1326
See also:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1093