Niobium(V) chloride

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Niobium(V) chloride
Sample of niobium(V) chloride
Names
IUPAC names
Niobium(V) chloride
Niobium pentachloride
Identifiers
3D model (
JSmol
)
ChemSpider
ECHA InfoCard
100.030.042 Edit this at Wikidata
EC Number
  • 233-059-8
RTECS number
  • QU0350000
UNII
  • InChI=1S/5ClH.Nb/h5*1H;/q;;;;;+5/p-5
    Key: YHBDIEWMOMLKOO-UHFFFAOYSA-I
  • Cl[Nb](Cl)(Cl)(Cl)Cl
  • dimer
    : Cl[Nb-]1(Cl)(Cl)(Cl)[Cl+][Nb-]([Cl+]1)(Cl)(Cl)(Cl)Cl
Properties
NbCl5
Molar mass 270.17 g/mol
Appearance yellow
deliquescent
Density 2.75 g/cm3
Melting point 204.7 °C (400.5 °F; 477.8 K)
Boiling point 248.2 °C (478.8 °F; 521.3 K)
decomposes
Solubility HCl, chloroform, CCl4
Thermochemistry
214.05 J K−1 mol−1
Std enthalpy of
formation
fH298)
-797.47 kJ/mol
Hazards
GHS labelling:
GHS05: CorrosiveGHS07: Exclamation mark
Danger
H302, H312, H314, H332
P260, P261, P264, P270, P271, P280, P301+P312, P301+P330+P331, P302+P352, P303+P361+P353, P304+P312, P304+P340, P305+P351+P338, P310, P312, P321, P322, P330, P363, P405, P501
Flash point Non-flammable
Related compounds
Other anions
Niobium(V) iodide
Other cations
Vanadium(IV) chloride
Tantalum(V) chloride
Related niobium chlorides
Niobium(III) chloride
Niobium(IV) chloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Niobium(V) chloride, also known as niobium pentachloride, is a yellow crystalline solid. It hydrolyzes in air, and samples are often contaminated with small amounts of

sublimation.[1]

Structure and properties

Ball-and-stick model of niobium pentachloride
Ball-and-stick model of niobium pentachloride

Niobium(V) chloride forms chloro-bridged dimers in the solid state (see figure). Each niobium centre is six-coordinate, but the octahedral coordination is significantly distorted. The equatorial niobium–chlorine

angle at the bridge is 101.3°. The Nb–Nb distance is 398.8 pm, too long for any metal-metal interaction.[2] NbBr5, NbI5, TaCl5
TaBr5 and TaI5 are isostructural with NbCl5.

Preparation

Niobium pentachloride liquid and vapor.

Industrially, niobium pentachloride is obtained by direct chlorination of niobium metal at 300 to 350 °C:[3]

2 Nb + 5 Cl2 → 2 NbCl5

In the laboratory, niobium pentachloride is often prepared from Nb2O5, the main challenge being incomplete reaction to give NbOCl3. The conversion can be effected with thionyl chloride:[4] It also can be prepared by chlorination of niobium pentoxide in the presence of carbon at 300 °C.

Uses

Niobium(V) chloride is the main precursor to the alkoxides of niobium, which find uses in

organoniobium compounds
.

In

Diels-Alder reaction. Niobium chloride can also generate N-acyliminium compounds from certain pyrrolidines which are substrates for nucleophiles such as allyltrimethylsilane, indole, or the silyl enol ether of benzophenone.[5]

References

External links