Vanadium trichloride

Vanadium(III) chloride

Names
IUPAC names Vanadium(III) chloride Vanadium trichloride
Identifiers
CAS Number	7718-98-1 Y
3D model (JSmol)	Interactive image
ChemSpider	10801024 Y
ECHA InfoCard	100.028.859
PubChem CID	62647
RTECS number	YW2800000
InChI InChI=1S/3ClH.V/h3*1H;/q;;;+3/p-3 Y Key: HQYCOEXWFMFWLR-UHFFFAOYSA-K Y InChI=1/3ClH.V/h3*1H;/q;;;+3/p-3 Key: HQYCOEXWFMFWLR-DFZHHIFOAB
SMILES [V+3].[Cl-].[Cl-].[Cl-]
Properties
Chemical formula	VCl3
Molar mass	157.30 g/mol
Appearance	violet crystals paramagnetic
Density	3.0 g/cm3 (20 °C)
Melting point	> 300 °C (572 °F; 573 K) (decomposes)
Solubility in water	soluble
Magnetic susceptibility (χ)	+3030.0·10−6 cm3/mol
Structure
Crystal structure	Trigonal, hR24
Space group	R-3, No. 148
Hazards
Flash point	Non-flammable
Related compounds
Other anions	vanadium trifluoride, vanadium(III) sulfide, vanadium tribromide
Other cations	titanium trichloride, chromium(III) chloride, niobium trichloride, tantalum trichloride
Related compounds	vanadium dichloride, vanadium tetrachloride
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
Y  (what is YN ?)
Infobox references

Vanadium trichloride is the inorganic compound with the formula VCl₃. This purple salt is a common precursor to other vanadium(III) complexes.

VCl₃ has the common BiI₃ structure, a motif that features hexagonally closest-packed chloride framework with vanadium ions occupying the octahedral holes. VBr₃ and VI₃ adopt the same structure, but VF₃ features a structure more closely related to ReO₃. VCl₃ is paramagnetic and has two unpaired electrons.

VCl₃ is prepared by heating VCl₄ at 160–170 °C under a flowing stream of inert gas, which sweeps out the Cl₂. The bright red liquid converts to a crusty purple solid. Further heating of VCl₃ decomposes with volatilization of VCl₄, leaving VCl₂. Upon heating under H₂ at 675 °C (but less than 700 °C), VCl₃ reduces to greenish VCl₂.

Vanadium trichloride catalyses the pinacol coupling reaction of benzaldehyde to 1,2-diphenyl-1,2-ethanediol by various reducing metals such as zinc:

VCl₃ forms many adducts and derivatives with a broad scale of colours. VCl₃ dissolves in water to give the hexahydrate, but the formula is deceptive. The salt is described by the formula [VCl₂(H₂O)₄]Cl^.2H₂O. In other words, two of the water molecules are not bound to the vanadium, whose structure resembles the corresponding Fe(III) derivative. Removal of the two bound chloride ligands from [VCl₂(H₂O)₄]⁺ in aqueous solution gives the green ion [V(H₂O)₆]³⁺.

With tetrahydrofuran, VCl₃ forms the red/pink adduct VCl₃(THF)₃. With acetonitrile, one obtains the green adduct VCl₃(MeCN)₃.

When treated with KCN, VCl₃ converts to [V(CN)₇]⁴⁻. It is common for early metals to adopt high coordination numbers (more than 6) with compact ligands. Complementarily, larger metals can form complexes with rather bulky ligands. This aspect is illustrated by the isolation of VCl₃(NMe₃)₂, containing two bulky NMe₃ ligands.