Harpoon reaction - Citizendia

Harpoon reactions^[1] are a type of chemical reaction between two substances one of them prone to form a cation, generally a metal, and the other one prone to form an anion, generally a halogen. A chemical reaction is a process that always results in the interconversion of Chemical substances The substance or substances initially involved in a chemical reaction are called An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge The M acro E xpansion T emplate A ttribute L anguage complements TAL, providing macros which allow the reuse of code across An ion is an Atom or Molecule which has lost or gained one or more Valence electrons giving it a positive or negative electrical charge Abundance Owing to their high Reactivity, the halogens are found in the environment only in compounds or as Ions Halide ions and oxoanions

Their main feature is that these reactions, unlike most reactions, have steric factors greater than unity, that is, they take place faster than predicted by collision theory. See also Collision theory Steric factor P is a term used in collision theory The reaction rate or rate of reaction for a Reactant or product in a particular reaction is intuitively defined as how fast a reaction takes The Collision theory, proposed by Max Trautz and William Lewis in 1916 and 1918 qualitatively explains how Chemical reactions occur and why Reaction This is explained by the fact that the colliding particles have greater cross sections than the pure geometrical ones calculated from their radii, because when the particles are close enough, an electron "jumps" (therefore the name) from one of the particles to the other one, forming an anion and a cation which subsequently attract each other. In nuclear and Particle physics, the concept of a cross section is used to express the likelihood of interaction between particles Harpoon reactions usually take place in the gas phase, but they are also possible in condensed media. This page is about the physical properties of gas as a state of matter ^[2]^[3]

The calculated rate constant can be improved by using a better estimation of the steric factor. In Chemical kinetics a reaction rate constant k or \lambda quantifies the speed of a Chemical reaction. A rough approximation is that the largest separation R_x at which charge transfer can take place on energetic grounds, can be estimated from the solution of the following equation that determines the largest distance at which the Coulombic attraction between the two oppositely charged ions is sufficient to provide the energy ΔE₀

$\frac{-e^2}{R_x}+\Delta E_0 = 0$ ^[4]

With $Δ E 0 = I P - E A$ , where IP is the ionization potential of the metal and EA is the electron affinity of the halogen. The ionization potential, ionization energy or EI of an Atom or Molecule is the Energy required to remove an Electron The electron affinity, E ea of an Atom or Molecule is the energy required to detach an electron from a singly charged negative

Examples of harpoon reactions

Generically: Rg + X₂ + hν → RgX + X,^[5] where Rg is a rare gas and X is a halogen
Ba. History Noble gas is translated from the German noun de ''Edelgas'' first used in 1898 by Hugo Erdmann to indicate their extremely low level of reactivity . . FCH₃ + hν → BaF^(*) + CH₃^[6]
K + CH₃I → KI + CH₃^[7]

References

^ IUPAC Goldbook definition of harpoon reaction
^ Fajardo, Mario E. ; V. A. Apkarian (November 15, 1986). Events 655 - Battle of Winwaed: Penda of Mercia is defeated by Oswiu of Northumbria. Year 1986 ( MCMLXXXVI) was a Common year starting on Wednesday (link displays 1986 Gregorian calendar) "Cooperative photoabsorption induced charge transfer reaction dynamics in rare gas solids. I. Photodynamics of localized xenon chloride exciplexes". The Journal of Chemical Physics 85 (10): 5660–5681. doi:10.1063/1.451579. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
^ Fajardo, Mario E. ; V. A. Apkarian (October 1, 1988). Events 331 BC - Alexander the Great defeats Darius III of Persia in the Battle of Gaugamela. Year 1988 ( MCMLXXXVIII) was a Leap year starting on Friday (link displays 1988 Gregorian calendar) "Charge transfer photodynamics in halogen doped xenon matrices. II. Photoinduced harpooning and the delocalized charge transfer states of solid xenon halides (F, Cl, Br, I)". The Journal of Chemical Physics 89 (7): 4102–4123. doi:10.1063/1.454846. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
^ 3
^ Okada, F. ; L. Wiedeman and V. A. Apkarian (February 23, 1989). "Photoinduced harpoon reactions as a probe of condensed-phase dynamics: iodine chloride in liquid and solid xenon" (PDF). Journal of Physical Chemistry 93 (4): 1267–1272. doi:10.1021/j100341a020. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.
^ Skowronek, S. ; J. B. Jiméne and A. González Ureña (8 July 1999). Events 939 - The Major Occultation or Ghaybat el-Kubra of Muhammad al-Mahdi 1099 - First Crusade: 15000 Year 1999 ( MCMXCIX) was a Common year starting on Friday (link will display full 1999 Gregorian calendar) "Resonances in the Ba...FCH₃ + hν → BaF + CH₃ reaction probability" (PDF). Journal of Chemical Physics 111 (4): 460–463.
^ Wiskerke, A. E. ; S. Stolte, H. J. Loesch and R. D. Levine (2000). "K + CH₃I → KI + CH₃ revisited: the total reaction cross section and its energy and orientation dependence. A case study of an intermolecular electron transfer". Physical Chemistry Chemical Physics 2 (4): 757–767. doi:10.1039/a907701d. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document.