Methylrhenium trioxide, also known as methyltrioxorhenium, is an organometallic compound with the formula CH₃ReO₃. It is a volatile, colourless solid has been used as a catalyst in some laboratory experiments. In this compound, Re has a tetrahedral coordination environment with one methyl and three oxo ligands. The oxidation state of rhenium is +7.

Synthesis

Methylrhenium trioxide is commercially available. It can be prepared by many routes, a typical method is the reaction of Re₂O₇ and tetramethyltin

Tetramethyltin

Tetramethyltin is an organometallic compound with the formula 4Sn. This liquid, one of the simplest organotin compounds, is useful for transition-metal mediated conversion of acid chlorides to methyl ketones and aryl halides to aryl methyl ketones...

:

Re₂O₇ + (CH₃)₄Sn → CH₃ReO₃ + (CH₃)₃SnOReO₃

Analogous alkyl and aryl derivatives are known. Compounds of the type RReO₃ are Lewis acid

Lewis acid

]The term Lewis acid refers to a definition of acid published by Gilbert N. Lewis in 1923, specifically: An acid substance is one which can employ a lone pair from another molecule in completing the stable group of one of its own atoms. Thus, H+ is a Lewis acid, since it can accept a lone pair,...

ic, forming both 1:1 and 1:2 adducts with halides and amines.

Uses

Methylrhenium trioxide serves as a heterogeneous catalyst for a variety of transformations. Supported on Al₂O₃/SiO₂, it catalyzes olefin metathesis

Olefin metathesis

Olefin metathesis or transalkylidenation is an organic reaction that entails redistribution of alkylene fragments by the scission of carbon - carbon double bonds in olefins . Its advantages include the creation of fewer sideproducts and hazardous wastes. Yves Chauvin, Robert H. Grubbs, and Richard R...

 at 25 °C.

In solution, MTO catalyses for the oxidations with hydrogen peroxide

Hydrogen peroxide

Hydrogen peroxide is the simplest peroxide and an oxidizer. Hydrogen peroxide is a clear liquid, slightly more viscous than water. In dilute solution, it appears colorless. With its oxidizing properties, hydrogen peroxide is often used as a bleach or cleaning agent...

. Terminal alkynes yield the corresponding acid or ester, internal alkynes yield diketones, and alkene

Alkene

In organic chemistry, an alkene, olefin, or olefine is an unsaturated chemical compound containing at least one carbon-to-carbon double bond...

s give epoxides. MTO also catalyses the conversion of aldehyde

Aldehyde

An aldehyde is an organic compound containing a formyl group. This functional group, with the structure R-CHO, consists of a carbonyl center bonded to hydrogen and an R group....

s and diazoalkanes into an alkene.