Isomers having the same number of each isotopic atom but differing in their positions. The term is a contraction of 'isotopic isomer'. Isotopomers can be either constitutional isomers (e.g.
CH2DCH=O and
CH3CD=O) or isotopic stereoisomers [e.g. (
R)- and (
S)-
CH3CHDOH or (
Z)- and (
E)-
CH3CH=CHD].
Sources:
PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1132 (https://doi.org/10.1351/pac199466051077)
PAC, 1996, 68, 2193. 'Basic terminology of stereochemistry (IUPAC Recommendations 1996)' on page 2211 (https://doi.org/10.1351/pac199668122193)