isogyric reaction

https://dx.doi.org/10.1351/goldbook.IT07060
A reaction in which the number of electron pairs is conserved, for example:
CH4(1A1) + H(2S)-->CH3(2A'2) + H2(1Σ+g)
Source:
PAC, 1999, 71, 1919 (Glossary of terms used in theoretical organic chemistry) on page 1947