In chemistry, redistribution usually refers to the exchange of anionic ligands bonded to metal and metalloid centers. The conversion does not involve

redox Redox (reduction–oxidation, , ) is a type of chemical reaction in which the oxidation states of substrate change. Oxidation is the loss of electrons or an increase in the oxidation state, while reduction is the gain of electrons or a ...

, in contrast to

disproportionation In chemistry, disproportionation, sometimes called dismutation, is a redox reaction in which one compound of intermediate oxidation state converts to two compounds, one of higher and one of lower oxidation states. More generally, the term can ...

reactions. Some useful redistribution reactions are conducted at higher temperatures; upon cooling the mixture, the product mixture is kinetically frozen and the individual products can be separated. In cases where redistribution is rapid at mild temperatures, the reaction is less useful synthetically but still important mechanistically.

Examples

Rapid redistribution reactions are exhibited by methylboranes. Thus monomethyldiborane rapidly converts at room temperature to

diborane Diborane(6), generally known as diborane, is the chemical compound with the formula B2H6. It is a toxic, colorless, and pyrophoric gas with a repulsively sweet odor. Diborane is a key boron compound with a variety of applications. It has attracte ...

and

trimethylborane Trimethylborane (TMB) is a toxic, pyrophoric gas with the formula B(CH3)3 (which can also be written as Me3B, with Me representing methyl). Properties As a liquid it is colourless. The strongest line in the infrared spectrum is at 1330 cm� ...

:. The authors refer to redistributions as "disproportionations". :6 MeB₂H₅ → 5 B₂H₆ + 2 Me₃B Useful redistribution reactions are found in organoaluminium,

organoboron Organoborane or organoboron compounds are chemical compounds of boron and carbon that are organic derivatives of BH3, for example trialkyl boranes. Organoboron chemistry or organoborane chemistry is the chemistry of these compounds. Organoboron ...

, and

organosilicon chemistry Organosilicon compounds are organometallic compounds containing carbon–silicon bonds. Organosilicon chemistry is the corresponding science of their preparation and properties. Most organosilicon compounds are similar to the ordinary organic c ...

. : BCl₃ + 2 B(C₂H₅)₃ → 3 BCl(C₂H₅)₂ In another example, tetramethylsilane is an undesirable product of the industrially important direct process, but it can be converted (recycled) into more useful products by redistribution with

silicon tetrachloride Silicon tetrachloride or tetrachlorosilane is the inorganic compound with the formula SiCl4. It is a colourless volatile liquid that fumes in air. It is used to produce high purity silicon and silica for commercial applications. Preparation Silic ...

: : SiMe₄ + SiCl₄ → 2 SiMe₂Cl₂ In

organotin chemistry Organotin compounds or stannanes are chemical compounds based on tin with hydrocarbon substituents. Organotin chemistry is part of the wider field of organometallic chemistry. The first organotin compound was diethyltin diiodide (), discovered b ...

, the mixed alkyl tin chlorides are produced by redistribution, a reaction called the Kocheshkov comproportionation: : 3 SnBu₄ + SnCl₄ → 4 SnBu₃Cl Many metal halides undergo redistribution reactions, usually to afford nearly statistical mixtures of products. For example,

titanium tetrachloride Titanium tetrachloride is the inorganic compound with the formula . It is an important intermediate in the production of titanium metal and the pigment titanium dioxide. is a volatile liquid. Upon contact with humid air, it forms thick clouds ...

and

titanium tetrabromide Titanium tetrabromide is the chemical compound with the formula TiBr4. It is the most volatile transition metal bromide. The properties of TiBr4 are an average of TiCl4 and TiI4. Some key properties of these four-coordinated Ti(IV) species ar ...

redistribute their halide ligands, one of many reactions in this conversion is shown: : TiCl₄ + TiBr₄ → 2 TiBr₂Cl₂

References

{{reflist Chemical reactions Chemical processes