Vanadium(III) chloride

VCl₃ has the common layered BiI₃ structure, a motif that features hexagonally closest-packed chloride framework with vanadium ions occupying the octahedral holes.{{Cite journal |last1=Mastrippolito |first1=Dario |last2=Camerano |first2=Luigi |last3=Świątek |first3=Hanna |last4=Šmíd |first4=Břetislav |last5=Klimczuk |first5=Tomasz |last6=Ottaviano |first6=Luca |last7=Profeta |first7=Gianni |date=2023-07-17 |title=Polaronic and Mott insulating phase of layered magnetic vanadium trihalide VCl3 |url=https://link.aps.org/doi/10.1103/PhysRevB.108.045126 |journal=Physical Review B |volume=108 |issue=4 |pages=045126 |doi=10.1103/PhysRevB.108.045126|arxiv=2301.06501 |s2cid=255942777 }} VBr₃ and VI₃ adopt the same structure, but VF₃ features a structure more closely related to ReO₃.{{cite journal |author1=Wilhelm Klemm |author2=Ehrhard Krose |title=Die Kristallstrukturen von ScCl₃, TiCl₃ und VCl₃ |journal=Zeitschrift für anorganische Chemie |date=1947 |volume=253 |issue=3–4 |pages=218–225 |doi=10.1002/zaac.19472530313 |trans-title=The Crystal Structures of ScCl₃, TiCl₃ and VCl₃ |language=de}} The V³⁺cation has a d² electronic configuration with two unpaired electrons, making the compound paramagnetic.Greenwood, N. N. and Earnshaw, A. (1997). Chemistry of the Elements (2nd Edn.), Oxford:Butterworth-Heinemann. p. 990 {{ISBN|0-7506-3365-4}}. VCl₃ is a Mott insulator and undergoes an antiferromagnetic transition at low temperatures.{{Cite journal |last1=Starr |first1=C. |last2=Bitter |first2=F. |last3=Kaufmann |first3=A. R. |date=1940-12-01 |title=The Magnetic Properties of the Iron Group Anhydrous Chlorides at Low Temperatures. I. Experimental |url=https://link.aps.org/doi/10.1103/PhysRev.58.977 |journal=Physical Review |volume=58 |issue=11 |pages=977–983 |doi=10.1103/PhysRev.58.977|bibcode=1940PhRv...58..977S }}

Solid hexahydrate, [VCl₂(H₂O)₄]Cl·2H₂O, has a monoclinic crystal structure and consists of slightly distorted octahedral trans-[VCl₂(H₂O)₄]⁺ centers as well as chloride and two molecules of water of crystallization.{{cite journal |author1=Fiona H. Fry |author2=Brenda Dougan |author3=Nichola McCann |author4=Anthony C. Willis |author5=Christopher J. Ziegler |author6=Nicola E. Brasch |title=Synthesis and X-ray structural characterization of tris(l-glycinato)vanadium(III) and trans-tetraquadichlorovanadium(III) chloride |journal=Inorganica Chimica Acta |date=2008 |volume=361 |issue=8 |pages=2321–2326 |doi=10.1016/j.ica.2007.11.025 |language=en}} The hexahydrate phase loses two water of crystallization to form the tetrahydrate if heated to 90 °C in a stream of hydrogen chloride gas.{{cite journal |author1=Sally M. Horner |author2=S. Y. Tyree |date=1964 |title=Chloro-Aquo Complexes of Vanadium(III) |journal=Inorganic Chemistry |language=en |volume=3 |issue=8 |pages=1173–1176 |doi=10.1021/ic50018a024}}

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| caption1 = Plan view of a single layer in the crystal structure of vanadium(III) chloride

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Solutions of vanadium(III) chloride in sulfuric acid and hydrochloric acid are used as electrolytes in vanadium redox batteries.{{cite book |author1=Günter Bauer |author2=Volker Güther |author3=Hans Hess |author4=Andreas Otto |author5=Oskar Roidl |author6=Heinz Roller |author7=Siegfried Sattelberger |author8=Sven Köther-Becker |author9=Thomas Beyer |title=Vanadium and Vanadium Compounds |date=2017 |publisher=Wiley-VCH Verlag GmbH & Co. KGaA. |isbn=978-3-527-30385-4 |page=16 |doi=10.1002/14356007.a27_367.pub2 |url=https://doi.org/10.1002/14356007.a27_367.pub2 |language=en}} It is also used as a mild Lewis acid in organic synthesis. One example of such is its use as a catalyst in the cleavage of the acetonide group.{{cite journal |author1=Gowravaram Sabitha |author2=G.S. Kiran Kumar Reddy |author3=K. Bhaskar Reddy |author4=N. Mallikarjuna Reddy |author5=J.S. Yadav |title=Vanadium(III) chloride: A mild and efficient catalyst for the chemoselective deprotection of acetonides |journal=Journal of Molecular Catalysis A: Chemical |date=2005 |volume=238 |issue=1–2 |pages=229–232 |doi=10.1016/j.molcata.2005.05.028 |language=en}} Another example of the use of VCl₃ as a reducing agent is shown in the determination of nitrate and nitrite concentration in water, where VCl₃ reduces nitrate to nitrite. This method is a safer alternative to the cadmium column method.{{cite journal |author1=Bernhard Schnetger |author2=Carola Lehners |title=Determination of nitrate plus nitrite in small volume marine water samples using vanadium(III)chloride as a reduction agent |journal=Marine Chemistry |date=2014 |volume=160 |pages=91–98 |doi=10.1016/j.marchem.2014.01.010 |bibcode=2014MarCh.160...91S |language=en}}

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 purple solid.{{cite book |author1=Georg Brauer |title=Handbuch der präparativen anorganischen Chemie Volume 3 |date=1975 |publisher=Enke |location=the University of Michigan |page=1409 |isbn=978-3-432-87823-2 |url=https://books.google.com/books?id=K9jvAAAAMAAJ |language=de}}

The vanadium oxides can also be used to produce vanadium(III) chloride. For example, vanadium(III) oxide reacts with thionyl chloride at 200 °C:

:V₂O₃ + 3 SOCl₂ → 2 VCl₃ + 3 SO₂

The reaction of vanadium(V) oxide and disulfur dichloride also produces vanadium(III) chloride with the release of sulfur dioxide and sulfur.

The hexahydrate can be prepared by evaporation of acidic aqueous solutions of the trichloride.

Heating of VCl₃ decomposes with volatilization of VCl₄, leaving VCl₂ above 350 °C.{{Cite book|doi = 10.1002/9780470132357.ch43|chapter = Vanadium(III) Chloride|title = Inorganic Syntheses|year = 2007|last1 = Young|first1 = Ralph C.|last2 = Smith|first2 = Maynard E.|last3 = Moeller|first3 = Therald|last4 = Gordon|first4 = Paul G.|last5 = McCullough|first5 = Fred|pages = 128–130|isbn = 978-0-470-13235-7}} Upon heating under H₂ at 675 °C (but less than 700 °C), VCl₃ reduces to greenish VCl₂.

:: 2 VCl₃ + H₂ → 2 VCl₂ + 2 HCl

Comproportionation of vanadium trichloride and vanadium(V) oxides gives vanadium oxydichloride:{{cite book|author=G. Brauer|chapter=Vanadium Oxydichloride|title=Handbook of Preparative Inorganic Chemistry, 2nd Ed. |editor=G. Brauer|publisher=Academic Press|year=1963|place=NY|pages=1263}}

:V₂O₅ + VOCl₃ + 3 VCl₃ → 6 VOCl₂

The heating of the hexahydrate does not give the anhydrous form, instead undergoes partial hydrolysis and forms vanadium oxydichloride at 160 °C. In an inert atmosphere, it forms a trihydrate at 130 °C and at higher temperatures, it forms vanadium oxychloride.{{cite book |author1=Ray Colton |author2=J. H. Canterford |title=Halides of the first row transition metals |date=1969 |publisher=Wiley |isbn=978-0-471-16625-2 |page=131 |language=en}}

Vanadium trichloride catalyses the pinacol coupling reaction of benzaldehyde (PhCHO) to 1,2-diphenyl-1,2-ethanediol by various reducing metals such as zinc:{{Cite journal|doi = 10.1021/jo051213f|title = Vanadium-Catalyzed Pinacol Coupling Reaction in Water|year = 2005|last1 = Xu|last2 = Hirao|first2 = Toshikazu|journal = The Journal of Organic Chemistry|volume = 70|issue = 21|pages = 8594–8596|pmid = 16209617}}

:Zn + 2 H₂O + 2 PhCHO → (PhCH(OH))₂ + Zn(OH)₂

VCl₃ forms colorful adducts and derivatives with a broad scale of ligands. VCl₃ dissolves in water to give the aquo complexes. From these solutions, the hexahydrate [VCl₂(H₂O)₄]Cl^.2H₂O crystallizes. 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 gives the green hexaaquo complex [V(H₂O)₆]³⁺.{{cite journal|doi=10.1039/DT9750000894|title=Crystal and Molecular Structures of Aquahalogenovanadium(III) Complexes. Part I. X-Ray Crystal Structure of trans-Tetrakisaquadibromo-Vanadium(III) Bromide Dihydrate and the Isomorphous Chloro- Compound|year=1975|last1=Donovan|first1=William F.|last2=Smith|first2=Peter W.|journal=Journal of the Chemical Society, Dalton Transactions|issue=10|page=894}}

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File:Vanadium(III) chloride solution.jpg

With tetrahydrofuran, VCl₃ forms the red/pink complex VCl₃(THF)₃,{{cite book |doi=10.1002/9780470132524.ch31|title=Inorganic Syntheses|year=1982|last1=Manzer|first1=L. E.|chapter=31. Tetragtdrfuran Complexes of Selected Early Transition Metals |pages=135–140|volume=21|isbn=978-0-471-86520-9 }} and zinc-powder reduction of the latter gives Caulton's reagent, [(V(THF)₃)₂Cl₃]₂[Zn₂Cl₆].{{cite encyclopedia|doi=10.1002/047084289X.rn02377|doi-broken-date=30 April 2025|url=https://onlinelibrary.wiley.com/doi/10.1002/047084289X.rn02377|access-date=30 April 2025|url-access=subscription|encyclopedia=Encyclopedia of Reagents for Organic Synthesis|title=Vanadium(1+), tri-μ‑chloro­hexakis(tetrahydrofuran)di-, di-μ‑chloro­tetrachloro­dizincate(2-) (2:1)|first1=Madhu|last1=Aeluri|first2=P. Andrew|last2=Evans|date=28 April 2023}}

Vanadium(III) chloride reacts with acetonitrile to give the green adduct VCl₃(MeCN)₃. When treated with KCN, VCl₃ converts to [V(CN)₇]⁴⁻ (early metals commonly adopt coordination numbers greater 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. Vanadium(III) chloride is able to form complexes with other adducts, such as pyridine or triphenylphosphine oxide.{{cite journal |author1=D. Nicholls |title=The coordination chemistry of vanadium |journal=Coordination Chemistry Reviews |date=1966 |volume=1 |issue=3 |pages=379–414 |doi=10.1016/S0010-8545(00)80145-9 |language=en}}

Vanadium(III) chloride as its thf complex is a precursor toV(mesityl)₃.{{Cite journal|doi=10.1021/om00029a042|title=Chemistry of the vanadium-carbon .sigma. Bond. 2. Oxovanadium(IV) and oxovanadium(V) containing metal-to-carbon .sigma. Bonds|year=1993|last1=Vivanco|first1=Marilin|last2=Ruiz|first2=Javier|last3=Floriani|first3=Carlo|last4=Chiesi-Villa|first4=Angiola|last5=Rizzoli|first5=Corrado|journal=Organometallics|volume=12|issue=5|pages=1802–1810}}

:: VCl₃(THF)₃ + 3 LiC₆H₂-2,4,6-Me₃ → V(C₆H₂-2,4,6-Me₃)₃(THF) + 3 LiCl

{{reflist}}

{{Vanadium compounds}}

{{Chlorides}}

{{DEFAULTSORT:Vanadium(Iii) Chloride}}

Category:Vanadium(III) compounds

Category:Chlorides

Category:Metal halides