isostructural reaction

A ligand exchange reaction, where the structural type of the metal complex remains the same.
MLn + X-->MLn-1X + L + ΔE
Although these types of reactions are not necessarily isodesmic reactions, a substantial degree of error cancellation for the calculated energy, ΔE, is achieved because the coordination sphere of the metal atom M is conserved.
Source:
PAC, 1999, 71, 1919 (Glossary of terms used in theoretical organic chemistry) on page 1948