Two or more
molecular entities are described as isoelectronic if they have the same number of
valence electrons and the same structure, i.e. number and
connectivity of atoms, but differ in some of the elements involved. Thus:
CO,
N2
and
NO+
are isoelectronic.
CH2=C=O
and
CH2=N=N
are isoelectronic.
CH3COCH3 and
CH3N=NCH3 have the same number of electrons, but have different structures, hence they are
not described as isoelectronic.
Source:
PAC, 1994, 66, 1077
(Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994))
on page 1128
