Molybdenum(V) chloride
Molybdenum(V) chloride is the inorganic compound with the empirical formula Template:Chem2. 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 Template:Chem2.[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 Template:Chem2.[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
Template:Chem2 is prepared by chlorination of Mo metal but also chlorination of Template:Chem2. The unstable hexachloride Template:Chem2 is not produced in this way.[5]
Template:Chem2 is reduced by acetonitrile to afford an orange acetonitrile complex, Template:Chem2. This complex in turn reacts with THF to give Template:Chem2, a precursor to other molybdenum-containing complexes.[6]
Molybdenum(IV) bromide is prepared by treatment of Template:Chem2 with hydrogen bromide:
The reaction proceeds via the unstable molybdenum(V) bromide, which releases bromine at room temperature.[7]
Template:Chem2 is a good Lewis acid toward non-oxidizable ligands. It forms an adduct with chloride to form Template:Chem2. In organic synthesis, the compound finds occasional use in chlorinations, deoxygenation, and oxidative coupling reactions.[8]
Reactions
Template:Chem2 is reduced by acetonitrile:[9]
Although it polymerizes tetrahydrofuran, Template:Chem2 is stable in diethyl ether. Reduction of such solutions with tin gives Template:Chem2 and Template:Chem2, depending on conditions.[10]
Safety considerations
Template:Chem2 is an aggressive oxidant and readily hydrolyzes to release HCl.
See also
References
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