Bromopentacarbonylrhenium(I)

Chembox new
ImageFile = Bromopentacarbonylrhenium(I)-3D-balls.png‎ ImageSize =
IUPACName = Bromidopentacarbonylrhenium
OtherNames =
Section1 = Chembox Identifiers
CASNo = 14220-21-4
PubChem =
SMILES =
Section2 = Chembox Properties
Formula = Re(CO)₅Br
MolarMass = 406.16 g/mol
Appearance = colorless
Density =
MeltingPt = sublimes 85-90 °C (0.2 mm Hg)
BoilingPt =
SolubleOther = soluble
Solvent = chlorocarbons
Section3 = Chembox Hazards
EUClass = Toxic (T)
FlashPt =
Autoignition =
RPhrases = R23/24/25 R36/37/38
SPhrases = S26 S28 S36/37/39 S45

Bromopentacarbonylrhenium(I) is an inorganic compound of rhenium, commonly used for the syntheses of other rhenium complexes.

Preparation

Bromopentacarbonylrhenium(I) is commercially available. It is also easily and inexpensively synthesized by the oxidation of dirhenium decacarbonyl with bromine: [cite journal | journal = Inorganic Syntheses | title = Pentacarbonylrhenium Halides | author = Steven P. Schmidt, William C. Trogler, Fred Basolo | volume = 28 | year = 1990 | pages = 154–159 | doi = 10.1002/9780470132593.ch42]

:Re₂(CO)₁₀ + Br₂ → 2 ReBr(CO)₅

It was first prepared by the "reductive carbonylation" of rhenium(III) bromide: [cite journal | author = W. Hieber, Mitarbeitern, Hans Schulten | title = XXX. Mitteilung über Metallcarbonyle. Über Rhenium-Kohlenoxyd-Verbindungen | journal = Zeitschrift für anorganische und allgemeine Chemie | year = 1939 | volume = 243 | pages = 164–173 | doi = 10.1002/zaac.19392430205] :ReBr₃ + 2 Cu + 5 CO → BrRe(CO)₅ + 2 CuBr

Reactions

Bromopentacarbonylrhenium(I) is a useful intermediate to other rhenium complexes. For example, it reacts with zinc and acetic acid to give pentacarbonylhydridorhenium (ReH(CO)₅).cite journal | author = Michael A. Urbancic, John R. Shapley | title = Pentacarbonylhydridorhenium | journal = Inorganic Syntheses | volume = 28 | pages = 165–8 | year = 1990 | doi = 10.1002/9780470132593.ch43] : Re(CO)₅Br + Zn + HO₂CCH₃ → ReH(CO)₅ + ZnBrO₂CCH₃

It also reacts with tetraethylammonium bromide in diglyme to give [NEt₄] ₂ [ReBr₃(CO)₃)] , an important precursor to compounds containing the rhenium tricarbonyl fragment. [cite journal | author = R. Alberto, A. Egli, U. Abram, K. Hegetschweiler, V. Gramlich and P. A. Schubiger | title = Synthesis and reactivity of [NEt₄] ₂ [ReBr₃(CO)₃] . Formation and structural characterization of the clusters [NEt₄] [Re₃(µ₃-OH)(µ-OH)₃(CO)₉] and [NEt₄] [Re₂(µ-OH)₃(CO)₆] by alkaline titration | year = 1994 | journal = J. Chem. Soc., Dalton Trans. | volume = | issue = | pages = 2815–2820 | doi = 10.1039/DT9940002815 | url = | ]

Refluxing bromopentacarbonylrhenium(I) in water also provides access to the rhenium tricarbonyl fragment:

:ReBr(CO)₅ + 3 H₂O → [Re(H₂O)(CO)₃] Br + 2 CO

This route avoids the formation of the tetraethylammonium bromide byproduct when the tetraethylammonium complex is used. This is desirable because the tetraethylammonium bromide is often difficult to remove from reaction mixtures. [cite journal | author = N. Lazarova, S. James, J. Babich and J. Zubieta | title = A convenient synthesis, chemical characterization and reactivity of [Re(CO)₃(H₂O)₃] Br: the crystal and molecular structure of [Re(CO)₃(CH₃CN)₂Br] | year = 2004 | journal = Inorganic Chemistry Communications | volume = 7 | issue = 9 | pages = 1023–1026 | doi = 10.1016/j.inoche.2004.07.006]

References