Molybdenum(V) chloride

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Molybdenum(V) chloride
IUPAC names
Molybdenum(V) chloride
Molybdenum pentachloride
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
  • 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
Molar mass 273.21 g/mol (MoCl5)
Appearancedark-green solid
Density 2.928 g/cm3
Melting point 194 °C (381 °F; 467 K)
Boiling point 268 °C (514 °F; 541 K)
Solubility soluble in dry ether, dry alcohol, organic solvents
edge-shared bioctahedron
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.



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]


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]

Molybdenum(VI) chloride can be prepared by treatment of MoF6 with bismuth trichloride. The hexachloride degrades to the pentachloride on standing. [11]

Safety considerations

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

Related Research Articles

<span class="mw-page-title-main">Acyl halide</span> Chemical compound

An acyl halide is a chemical compound derived from an oxoacid by replacing a hydroxyl group with a halide group.

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

Palladium(II) chloride, also known as palladium dichloride and palladous chloride, are the chemical compounds with the formula PdCl2. PdCl2 is a common starting material in palladium chemistry – palladium-based catalysts are of particular value in organic synthesis. It is prepared by the reaction of chlorine with palladium metal at high temperatures.

<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.

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

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

Tungsten hexachloride is the chemical compound of tungsten and chlorine with the formula WCl6. This dark violet blue species exists as a volatile solid under standard conditions. It is an important starting reagent in the preparation of tungsten compounds. Other examples of charge-neutral hexachlorides are ReCl6 and MoCl6. The highly volatile WF6 is also known.

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

Tungsten(V) chloride is an inorganic compound with the formula W2Cl10. This compound is analogous in many ways to the more familiar molybdenum pentachloride.

Sulfonyl halide groups occur when a sulfonyl functional group is singly bonded to a halogen atom. They have the general formula RSO2X where X is a halogen. The stability of sulfonyl halides decreases in the order fluorides > chlorides > bromides > iodides, all four types being well known. The sulfonyl chlorides and fluorides are of dominant importance in this series.

<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">Hexafluorophosphate</span> Anion with the chemical formula PF6–

Hexafluorophosphate is an anion with chemical formula of [PF6]. It is an octahedral species that imparts no color to its salts. [PF6] is isoelectronic with sulfur hexafluoride, SF6, and the hexafluorosilicate dianion, [SiF6]2−, and hexafluoroantimonate [SbF6]. In this anion, phosphorus has a valence of 5. Being poorly nucleophilic, hexafluorophosphate is classified as a non-coordinating anion.

<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

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<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 allyl complex</span>

Transition-metal allyl complexes are coordination complexes with allyl and its derivatives as ligands. Allyl is the radical with the connectivity CH2CHCH2, although as a ligand it is usually viewed as an allyl anion CH2=CH−CH2, which is usually described as two equivalent resonance structures.

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

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

Tungsten(II) chloride is the inorganic compound with the formula W6Cl12. It is a polymeric cluster compound. The material dissolves in concentrated hydrochloric acid, forming (H3O)2[W6Cl14](H2O)x. Heating this salt gives yellow-brown W6Cl12. The structural chemistry resembles that observed for molybdenum(II) chloride.

<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">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.


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