Molybdenum(V) chloride
Partially oxidized MoCl5
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| IUPAC names
Molybdenum(V) chloride
Molybdenum pentachloride | |
| Identifiers | |
3D model (JSmol)
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| E number | Lua error in Module:Wikidata at line 880: attempt to index field 'wikibase' (a nil value). |
PubChem CID
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| UNII | |
| UN number | 2508 |
CompTox Dashboard (EPA)
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| Properties | |
| Mo2Cl10 | |
| Molar mass | 273.21 g/mol (MoCl5) |
| Appearance | dark-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
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oxidizer, hydrolyzes to release HCl |
| GHS labelling:[1] | |
| GHS05: Corrosive | |
| Danger | |
| H314 | |
| P260, P264, P280, P301+P330+P331, P302+P361+P354, P304+P340, P305+P354+P338, P316, P321, P363, P405, P501 | |
| Flash point | Non-flammable |
| Related compounds | |
Other anions
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Other cations
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Related molybdenum chlorides
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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.
Structure
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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
[edit | edit source]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:[6]
- 2 MoCl5 + 5 CH3CN → 2 MoCl4(CH3CN)2 + HCl + ClCH2CN
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]
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.[9]
Safety considerations
[edit | edit source]MoCl5 is an aggressive oxidant and readily hydrolyzes to release HCl.
See also
[edit | edit source]References
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