Methylrhenium trioxide

Methylrhenium trioxide
Other names methyltrioxorhenium
Identifiers
CAS number	70197-13-6 Y
	Properties
Molecular formula	CH3ReO3
Molar mass	249.24 g/mol
Appearance	white powder
Melting point	112 °C (385 K)
Solubility in water	highly soluble in water
Hazards
MSDS	External MSDS
S-phrases	S22, S23, S24/25
Y (verify) (what is: Y/N?) Except where noted otherwise, data are given for materials in their standard state (at 25 °C (77 °F), 100 kPa)
Infobox references

Methylrhenium trioxide, also known as methyltrioxorhenium, is an organometallic compound with the formula CH₃ReO₃. It is a volatile, colourless solid that has been used as a catalyst in some laboratory experiments. In this compound, Re has a tetrahedral coordination geometry 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:^[1]

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

Analogous alkyl and aryl derivatives are known. Compounds of the type RReO₃ are Lewis acids, 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 at 25 °C.

In solution, MTO catalyses for the oxidations with hydrogen peroxide. Terminal alkynes yield the corresponding acid or ester, internal alkynes yield diketones, and alkenes give epoxides. MTO also catalyses the conversion of aldehydes and diazoalkanes into an alkene.^[2]

References

1. ↑ Herrmann, W. A.; Kratzer R. M.; Fischer R. W. (1997). "Alkylrhenium Oxides from Perrhenates: A New, Economical Access to Organometallic Oxide Catalysts". Angew. Chem. Int. Ed. Engl. 36 (23): 2652–2654. doi:10.1002/anie.199726521. 
2. ↑ Hudson, A. “Methyltrioxorhenium” Encyclopedia of Reagents for Organic Synthesis. John Wiley & Sons: New York, 2002.