A reversible or irreversible reaction that involves the introduction of a @G02711@ species into a host structure and that results in significant structural modifications to the host, for example, the breakage of bonds. Example: The @I03058@ of lithium at \(50\,^{\unicode{x26ac}}\text{C}\) into the spinel Li[Mn₂]O₄ with symmetry \(F\,\text{d3m}\) to yield a layered structure with symmetry \(P\bar{3}\,\text{m1}\). Alternative terms: topotactic reaction, @I03058@ reaction.