insertion

https://doi.org/10.1351/goldbook.I03058
  1. A chemical reaction or transformation of the general type:
    I03058-1.png
    in which the connecting atom or group Y replaces the bond joining the parts X and Z of the reactant XZ. An example is the carbene insertion reaction:
    I03058-2.png
    The reverse of an insertion is called an extrusion.
    See also: α-addition
    Source:
    PAC, 1994, 66, 1077. 'Glossary of terms used in physical organic chemistry (IUPAC Recommendations 1994)' on page 1125 (https://doi.org/10.1351/pac199466051077)
  2. A general term given to a reaction involving the transfer of a guest atom, ion or molecule into a host crystal lattice.
    See: intercalation reaction, topochemical reaction
    Source:
    PAC, 1994, 66, 577. 'Definitions of terms relating to phase transitions of the solid state (IUPAC Recommendations 1994)' on page 583 (https://doi.org/10.1351/pac199466030577)