This is analogous to the process of ligand insertion in coordination chemistry.
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This reaction might also be imagined to proceed by adsorption of
C2H4 followed by ligand migration (an associative surface reaction).
Source:
PAC, 1976, 46, 71. 'Manual of Symbols and Terminology for Physicochemical Quantities and Units - Appendix II. Definitions, Terminology and Symbols in Colloid and Surface Chemistry. Part II: Heterogeneous Catalysis' on page 84 (https://doi.org/10.1351/pac197646010071)