Bromopentacarbonylrhenium(I) Explained
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:[1]
Re2(CO)10 + Br2 → 2 ReBr(CO)5
It was first prepared by the "reductive carbonylation" of rhenium(III) bromide:[2]
ReBr3 + 2 Cu + 5 CO → BrRe(CO)5 + 2 CuBr
Copper(I) bromide is a byproduct.
Reactions
Bromopentacarbonylrhenium(I) is a precursor to other rhenium complexes. It reacts with zinc and acetic acid to give pentacarbonylhydridorhenium (HRe(CO)5).[3]
Re(CO)5Br + Zn + HO2CCH3 → ReH(CO)5 + ZnBrO2CCH3
It also reacts with tetraethylammonium bromide in diglyme to give [NEt<sub>4</sub>]2[ReBr<sub>3</sub>(CO)<sub>3</sub>)], an important precursor to compounds containing the rhenium tricarbonyl fragment.[4]
Heating bromopentacarbonylrhenium(I) in water give the triaquo complex:
ReBr(CO)5 + 3 H2O → [Re(H<sub>2</sub>O)<sub>3</sub>(CO)<sub>3</sub>]Br + 2 CO
This route avoids the formation of the tetraethylammonium bromide byproduct, which is often difficult to remove from reaction mixtures.[5]
Notes and References
- Book: Pentacarbonylrhenium Halides . Steven P. Schmidt . William C. Trogler . Fred Basolo . 28 . 1990 . 154–159 . 10.1002/9780470132593.ch42 . Inorganic Syntheses . 9780470132593.
- W. Hieber . Hans Schulten . XXX. Mitteilung über Metallcarbonyle. Über Rhenium-Kohlenoxyd-Verbindungen . Zeitschrift für anorganische und allgemeine Chemie . 1939 . 243 . 164–173 . 10.1002/zaac.19392430205 . 2.
- Book: Michael A. Urbancic . John R. Shapley . Pentacarbonylhydridorhenium . 28 . 165–8 . 1990 . 10.1002/9780470132593.ch43 . Inorganic Syntheses . 9780470132593.
- R. Alberto . A Egli . U. Abram . K. Hegetschweiler . V. Gramlich . P. A. Schubiger . amp. Synthesis and Reactivity of [NEt<sub>4</sub>]2[ReBr<sub>3</sub>(CO)<sub>3</sub>]. Formation and Structural Characterization of the Clusters [NEt<sub>4</sub>][Re<sub>3</sub>(μ<sub>3</sub>-OH)(μ-OH)<sub>3</sub>(CO)<sub>9</sub>] and [NEt<sub>4</sub>][Re<sub>2</sub>(μ-OH)<sub>3</sub>(CO)<sub>6</sub>] by alkaline titration . 1994 . . 19. 2815–2820 . 10.1039/DT9940002815.
- N. Lazarova . S. James . J. Babich . J. Zubieta . amp . A convenient synthesis, chemical characterization and reactivity of [Re(CO)<sub>3</sub>(H<sub>2</sub>O)<sub>3</sub>]Br: the crystal and molecular structure of [Re(CO)<sub>3</sub>(CH<sub>3</sub>CN)<sub>2</sub>Br] . 2004 . . 7 . 9 . 1023–1026 . 10.1016/j.inoche.2004.07.006.
