Molybdenum(V) chloride

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Molybdenum(V) chloride
Mo2Cl10Sttructure.png
Molybdenum(V)-chloride-from-xtal-3D-balls.png
Molybdenum pentachloride.png
Partially oxidized MoCl5
Names
IUPAC names
Molybdenum(V) chloride
Molybdenum pentachloride
Identifiers
3D model (JSmol)
ECHA InfoCard 100.030.510 OOjs UI icon edit-ltr-progressive.svg
EC Number
  • 233-575-3
PubChem CID
RTECS number
  • QA4690000
UNII
  • InChI=1S/5ClH.Mo/h5*1H;/q;;;;;+5/p-5
  • InChI=1S/10ClH.2Mo/h10*1H;;/q;;;;;;;;;;2*+4/p-8
  • Cl[Mo](Cl)(Cl)(Cl)Cl
  • Cl1[Mo](Cl)(Cl)(Cl)(Cl)Cl[Mo]1(Cl)(Cl)(Cl)Cl
Properties
Mo2Cl10
Molar mass 273.21 g/mol (MoCl5)
Appearancedark-green solid
hygroscopic
paramagnetic
Density 2.928 g/cm3
Melting point 194 °C (381 °F; 467 K)
Boiling point 268 °C (514 °F; 541 K)
hydrolyzes
Solubility soluble in dry ether, dry alcohol, organic solvents
Structure
monoclinic
edge-shared bioctahedron
Hazards
Occupational safety and health (OHS/OSH):
Main hazards
oxidizer, hydrolyzes to release HCl
Flash point Non-flammable
Related compounds
Other anions
Other cations
Related molybdenum chlorides
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
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Molybdenum(V) chloride is the inorganic compound with the empirical formula MoCl5. This dark volatile solid is used in research to prepare other molybdenum compounds. It is moisture-sensitive and soluble in chlorinated solvents.

Contents

Structure

Usually called molybdenum pentachloride, it is in fact partly a dimer with the molecular formula Mo2Cl10. [1] In the dimer, each molybdenum has local octahedral symmetry and two chlorides bridge between the molybdenum centers. [2] A similar structure is also found for the pentachlorides of W, Nb and Ta. [3] In the gas phase and partly in solution, the dimers partially dissociate to give a monomeric MoCl5. [4] The monomer is paramagnetic, with one unpaired electron per Mo center, reflecting the fact that the formal oxidation state is +5, leaving one valence electron on the metal center.

Preparation and properties

MoCl5 is prepared by chlorination of Mo metal but also chlorination of MoO3. The unstable hexachloride MoCl6 is not produced in this way. [5]

MoCl5 is reduced by acetonitrile to afford an orange acetonitrile complex, MoCl4(CH3CN)2. This complex in turn reacts with THF to give MoCl4(THF)2, a precursor to other molybdenum-containing complexes. [6]

Molybdenum(IV) bromide is prepared by treatment of MoCl5 with hydrogen bromide:

2 MoCl5 + 10 HBr → 2 MoBr4 + 10 HCl + Br2

The reaction proceeds via the unstable molybdenum(V) bromide, which releases bromine at room temperature. [7]

MoCl5 is a good Lewis acid toward non-oxidizable ligands. It forms an adduct with chloride to form [MoCl6]. In organic synthesis, the compound finds occasional use in chlorinations, deoxygenation, and oxidative coupling reactions. [8]

Reactions

MoCl5 is reduced by acetonitrile: [9]

2 MoCl5 + 5 CH3CN → 2 MoCl4(CH3CN)2 + HCl + ClCH2CN

Although it polymerizes tetrahydrofuran, MoCl5 is stable in diethyl ether. Reduction of such solutions with tin gives MoCl4((CH3CH2)2O)2 and MoCl3((CH3CH2)2O)3, depending on conditions. [10]

Safety considerations

MoCl5 is an aggressive oxidant and readily hydrolyzes to release HCl.

See also

Related Research Articles

<span class="mw-page-title-main">Niobium(V) chloride</span> Chemical compound

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 NbOCl3. It is often used as a precursor to other compounds of niobium. NbCl5 may be purified by sublimation.

<span class="mw-page-title-main">Tantalum(V) chloride</span> Chemical compound

Tantalum(V) chloride, also known as tantalum pentachloride, is an inorganic compound with the formula TaCl5. It takes the form of a white powder and is commonly used as a starting material in tantalum chemistry. It readily hydrolyzes to form tantalum(V) oxychloride (TaOCl3) and eventually tantalum pentoxide (Ta2O5); this requires that it be synthesised and manipulated under anhydrous conditions, using air-free techniques.

Titanium(III) chloride is the inorganic compound with the formula TiCl3. At least four distinct species have this formula; additionally hydrated derivatives are known. TiCl3 is one of the most common halides of titanium and is an important catalyst for the manufacture of polyolefins.

Vanadium tetrachloride is the inorganic compound with the formula VCl4. This reddish-brown liquid serves as a useful reagent for the preparation of other vanadium compounds.

<span class="mw-page-title-main">Tungsten hexacarbonyl</span> Chemical compound

Tungsten hexacarbonyl (also called tungsten carbonyl) is an organometallic compound with the formula W(CO)6. This complex gave rise to the first example of a dihydrogen complex.

<span class="mw-page-title-main">Nitrosyl chloride</span> Chemical compound

Nitrosyl chloride is the chemical compound with the formula NOCl. It is a yellow gas that is commonly encountered as a component of aqua regia, a mixture of 3 parts concentrated hydrochloric acid and 1 part of concentrated nitric acid. It is a strong electrophile and oxidizing agent. It is sometimes called Tilden's reagent, after William A. Tilden, who was the first to produce it as a pure compound.

<span class="mw-page-title-main">Molybdenum(II) chloride</span> Chemical compound

Molybdenum dichloride describes chemical compounds with the empirical formula MoCl2. At least two forms are known, and both have attracted much attention from academic researchers because of the unexpected structures seen for these compounds and the fact that they give rise to hundreds of derivatives. The form discussed here is Mo6Cl12. The other molybdenum(II) chloride is potassium octachlorodimolybdate.

<span class="mw-page-title-main">Cyclopentadienylmolybdenum tricarbonyl dimer</span> Chemical compound

Cyclopentadienylmolybdenum tricarbonyl dimer is the chemical compound with the formula Cp2Mo2(CO)6, where Cp is C5H5. A dark red solid, it has been the subject of much research although it has no practical uses.

Niobocene dichloride is the organometallic compound with the formula (C5H5)2NbCl2, abbreviated Cp2NbCl2. This paramagnetic brown solid is a starting reagent for the synthesis of other organoniobium compounds. The compound adopts a pseudotetrahedral structure with two cyclopentadienyl and two chloride substituents attached to the metal. A variety of similar compounds are known, including Cp2TiCl2.

<span class="mw-page-title-main">Rhenium pentachloride</span> Chemical compound

Rhenium pentachloride is an inorganic compound of chlorine and rhenium. The compound has the formula Re2Cl10 but it is usually referred to as rhenium pentachloride. It is a red-brown solid.

<span class="mw-page-title-main">Molybdenum tetrachloride</span> Chemical compound

Molybdenum tetrachloride is the inorganic compound with the empirical formula MoCl4. The material exists as two polymorphs, both being dark-colored paramagnetic solids. These compounds are mainly of interest as precursors to other molybdenum complexes.

<span class="mw-page-title-main">Niobium(IV) chloride</span> Chemical compound

Niobium(IV) chloride, also known as niobium tetrachloride, is the chemical compound of formula NbCl4. This compound exists as dark violet crystals, is highly sensitive to air and moisture, and disproportiates into niobium(III) chloride and niobium(V) chloride when heated.

<span class="mw-page-title-main">Metal halides</span>

Metal halides are compounds between metals and halogens. Some, such as sodium chloride are ionic, while others are covalently bonded. A few metal halides are discrete molecules, such as uranium hexafluoride, but most adopt polymeric structures, such as palladium chloride.

<span class="mw-page-title-main">Molybdenum(III) chloride</span> Chemical compound

Molybdenum(III) chloride is the inorganic compound with the formula MoCl3. It forms purple crystals.

<span class="mw-page-title-main">Bis(dinitrogen)bis(1,2-bis(diphenylphosphino)ethane)molybdenum(0)</span> Chemical compound

trans-Bis(dinitrogen)bis[1,2-bis(diphenylphosphino)ethane]molybdenum(0) is a coordination complex with the formula Mo(N2)2(dppe)2. It is a relatively air stable yellow-orange solid. It is notable as being the first discovered dinitrogen containing complex of molybdenum.

<span class="mw-page-title-main">Transition metal nitrile complexes</span> Class of coordination compounds containing nitrile ligands (coordinating via N)

Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile.

<span class="mw-page-title-main">Tungsten(III) chloride</span> Chemical compound

Tungsten(III) chloride is the inorganic compound with the formula W6Cl18. It is a cluster compound. It is a brown solid, obtainable by chlorination of tungsten(II) chloride. Featuring twelve doubly bridging chloride ligands, the cluster adopts a structure related to the corresponding chlorides of niobium and tantalum. In contrast, W6Cl12 features eight triply bridging chlorides.

<span class="mw-page-title-main">Molybdenum oxytetrachloride</span> Chemical compound

Molybdenum oxytetrachloride is the inorganic compound with the formula MoOCl4. This thermally unstable, dark green solid is used to prepare other complexes of molybdenum. It adopts a square pyramidal structure of C4v symmetry. As for other Mo(VI) compounds, it is diamagnetic. It decomposes thermally to MoOCl3.

<span class="mw-page-title-main">Transition metal chloride complex</span> Coordination complex

In chemistry, a transition metal chloride complex is a coordination complex that consists of a transition metal coordinated to one or more chloride ligand. The class of complexes is extensive.

<span class="mw-page-title-main">Transition metal ether complex</span>

In chemistry, a transition metal ether complex is a coordination complex consisting of a transition metal bonded to one or more ether ligand. The inventory of complexes is extensive. Common ether ligands are diethyl ether and tetrahydrofuran. Common chelating ether ligands include the glymes, dimethoxyethane (dme) and diglyme, and the crown ethers. Being lipophilic, metal-ether complexes often exhibit solubility in organic solvents, a property of interest in synthetic chemistry. In contrast, the di-ether 1,4-dioxane is generally a bridging ligand.

References

  1. Holleman, A. F.; Wiberg, E. (2001). Inorganic Chemistry. San Diego, CA: Academic Press. ISBN   0-12-352651-5.
  2. Beck, J.; Wolf, F. (1997). "Three New Polymorphic Forms of Molybdenum Pentachloride". Acta Crystallogr. B53 (6): 895–903. doi:10.1107/S0108768197008331. S2CID   95489209.
  3. Wells, A. E. (1984). Structural Inorganic Chemistry (5th ed.). Oxford: Clarendon Press.
  4. Brunvoll, J.; Ischenko, A. A.; Spiridonov, V. P.; Strand, T. G. (1984). "Composition and Molecular Structure of Gaseous Molybdenum Pentachloride by Electron Diffraction". Acta Chem. Scand. A38: 115–120. doi: 10.3891/acta.chem.scand.38a-0115 .
  5. Tamadon, Farhad; Seppelt, Konrad (2013). "The Elusive Halides VCl5, MoCl6, and ReCl6". Angew. Chem. Int. Ed. 52 (2): 767–769. doi:10.1002/anie.201207552. PMID   23172658.
  6. Dilworth, Jonathan R.; Richards, Raymond L. (1990). "The Synthesis of Molybdenum and Tungsten Dinitrogen Complexes". Inorganic Syntheses. Inorganic Syntheses. Vol. 28. pp. 33–43. doi:10.1002/9780470132593.ch7. ISBN   9780470132593.
  7. Calderazzo, Fausto; Maichle-Mössmer, Cäcilie; Pampaloni, Guido; Strähle, Joachim (1993). "Low-Temperature Syntheses of Vanadium(III) and Molybdenum(IV) Bromides by Halide Exchange". J. Chem. Soc., Dalton Trans. (5): 655–658. doi:10.1039/DT9930000655.
  8. Kauffmann, T.; Torii, S.; Inokuchi, T. (2004). "Molybdenum(V) Chloride". Encyclopedia of Reagents for Organic Synthesis. New York, NY: J. Wiley & Sons. doi:10.1002/047084289X. hdl: 10261/236866 . ISBN   9780471936237.
  9. Dilworth, Jonathan R.; Richards, Raymond L. (1990). The Synthesis of Molybdenum and Tungsten Dinitrogen Complexes. Inorganic Syntheses. Vol. 28. pp. 33–43. doi:10.1002/9780470132593.ch7. ISBN   9780470132593.
  10. Maria, Sébastien; Poli, Rinaldo (2014). "Ether Complexes of Molybdenum(III) and Molybdenum(IV) chlorides". Inorganic Syntheses: Volume 36 (PDF). Inorganic Syntheses. Vol. 36. pp. 15–18. doi:10.1002/9781118744994.ch03. ISBN   9781118744994.