Protactinium(V) bromide is an inorganic compound. It is a halide of

protactinium Protactinium (formerly protoactinium) is a chemical element with the symbol Pa and atomic number 91. It is a dense, silvery-gray actinide metal which readily reacts with oxygen, water vapor and inorganic acids. It forms various chemical compounds ...

, consisting of protactinium and

bromine Bromine is a chemical element with the symbol Br and atomic number 35. It is the third-lightest element in group 17 of the periodic table ( halogens) and is a volatile red-brown liquid at room temperature that evaporates readily to form a simi ...

. It is radioactive and has a

chemical formula In chemistry, a chemical formula is a way of presenting information about the chemical proportions of atoms that constitute a particular chemical compound or molecule, using chemical element symbols, numbers, and sometimes also other symbol ...

of PaBr₅, which is a red

crystal A crystal or crystalline solid is a solid material whose constituents (such as atoms, molecules, or ions) are arranged in a highly ordered microscopic structure, forming a crystal lattice that extends in all directions. In addition, macro ...

of the

monoclinic crystal system In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

Preparation

Protactinium(V) bromide can be obtained by reacting

protactinium(V) chloride Protactinium(V) chloride is the chemical compound composed of protactinium and chlorine with the formula PaCl5. It forms yellow monoclinic crystals and has a unique structure composed of chains of 7 coordinate, pentagonal bipyramidal, protactiniu ...

with

boron tribromide Boron tribromide, BBr3, is a colorless, fuming liquid compound containing boron and bromine. Commercial samples usually are amber to red/brown, due to weak bromine contamination. It is decomposed by water and alcohols. Chemical properties Boron ...

at 500 to 550 °C.

Georg Brauer Georg Karl Brauer (born 11. April 1908 in Bochum, died 26. February 2001 in Freiburg im Breisgau) was a German chemist. Life Brauer was the son of the chemist Eberhard Brauer and Elisabeth Brauer, a daughter of Wilhelm Ostwald. From 1926 to 1932 ...

(Hrsg.), unter Mitarbeit von

Marianne Baudler Marianne Baudler (27 April 1921 – 5 March 2003) was a German chemist. She is known for her research on phosphorus. Life Marianne Baudler was born in Stettin. She started studying Chemistry at the TH Dresden in April 1940 and finished her studi ...

u. a.: ''Handbuch der Präparativen Anorganischen Chemie.'' 3., umgearbeitete Auflage. Band I, Ferdinand Enke, Stuttgart 1975, ISBN 3-432-02328-6, S. 1177. :3PaCl₅ + 5BBr₃ → 3PaBr₅ + 5BCl₃ It can also be obtained by reacting protactinium(V) oxide with aluminum bromide at 400 °C.

Physical properties

Protactinium(V) bromide is an orange-red, crystalline, extremely moisture-sensitive solid that reacts violently with

water Water (chemical formula ) is an Inorganic compound, inorganic, transparent, tasteless, odorless, and Color of water, nearly colorless chemical substance, which is the main constituent of Earth's hydrosphere and the fluids of all known living ...

and

ammonia Ammonia is an inorganic compound of nitrogen and hydrogen with the formula . A stable binary hydride, and the simplest pnictogen hydride, ammonia is a colourless gas with a distinct pungent smell. Biologically, it is a common nitrogenous wa ...

, but is persistent in absolutely dry air. It is insoluble in

isopentane Isopentane, also called methylbutane or 2-methylbutane, is a branched-chain saturated hydrocarbon (an alkane) with five carbon atoms, with formula or . Isopentane is an extremely volatile and extremely flammable liquid at room temperature and ...

, dichloromethane and

benzene Benzene is an organic chemical compound with the molecular formula C6H6. The benzene molecule is composed of six carbon atoms joined in a planar ring with one hydrogen atom attached to each. Because it contains only carbon and hydrogen atoms ...

, and in anhydrous acetonitrile is dissolves to form PaBr₅•4CH₃CN. It comes in several modifications. Below 400 °C as an α-modification and above 400 °C as a β-modification. The α-form has a

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic s ...

crystal structure In crystallography, crystal structure is a description of the ordered arrangement of atoms, ions or molecules in a crystalline material. Ordered structures occur from the intrinsic nature of the constituent particles to form symmetric patterns ...

of the

space group In mathematics, physics and chemistry, a space group is the symmetry group of an object in space, usually in three dimensions. The elements of a space group (its symmetry operations) are the rigid transformations of an object that leave it uncha ...

''P''2₁/''c'' (No. 14) and

lattice parameter A lattice constant or lattice parameter is one of the physical dimensions and angles that determine the geometry of the unit cells in a crystal lattice, and is proportional to the distance between atoms in the crystal. A simple cubic crystal has o ...

s ''a'' = 1296 pm, ''b'' = 1282 pm, ''c'' = 992 pm, β = 108° and the β-form also has monoclinic crystal structure with space group ''P''2₁/''n'' (No. 14, position 2) and lattice parameters ''a'' = 838.5 pm, ''b'' = 1120.5 pm, ''c'' = 895.0 pm, β = 91.1°. The β form exists as a

dimer Dimer may refer to: * Dimer (chemistry), a chemical structure formed from two similar sub-units ** Protein dimer, a protein quaternary structure ** d-dimer * Dimer model, an item in statistical mechanics, based on ''domino tiling'' * Julius Dimer ...

. At 400 °C in a vacuum, protactinium(V) bromide sublimes.D. Brown, T. J. Petcher, A. J. Smith: ''The crystal structure of β-protactinium pentabromide.'' In: ''Acta Crystallographica Section B Structural Crystallography and Crystal Chemistry.'' 25, S. 178–182, . A γ-form, which has a β- uranium(V) chloride-type crystal structure, has also been detected.D. Brown: ''The polymorphism of protactinium pentabromide.'' In: ''Inorganic and Nuclear Chemistry Letters.'' 15, 1979, S. 219–223, .

References

{{Actinide halides Bromides Actinide halides Protactinium(V) compounds