Molybdenum tetrachloride is the

inorganic compound In chemistry, an inorganic compound is typically a chemical compound that lacks carbon–hydrogen bonds, that is, a compound that is not an organic compound. The study of inorganic compounds is a subfield of chemistry known as '' inorganic chemi ...

with the empirical formula MoCl₄. The material exists as two

polymorph Polymorphism, polymorphic, polymorph, polymorphous, or polymorphy may refer to: Computing * Polymorphism (computer science), the ability in programming to present the same programming interface for differing underlying forms * Ad hoc polymorphi ...

s, both being dark-colored paramagnetic solids. These compounds are mainly of interest as precursors to other molybdenum complexes.

Structure

The α polymorph is a polymer. The β polymorph is a hexamer. In both polymorph, the Mo center is octahedral with two terminal chloride ligands and four doubly bridging ligands. In addition to these two binary phases, a number of adducts are know with the formula where L is a

Lewis base A Lewis acid (named for the American physical chemist Gilbert N. Lewis) is a chemical species that contains an empty orbital which is capable of accepting an electron pair from a Lewis base to form a Lewis adduct. A Lewis base, then, is any sp ...

Preparation

α-Molybdenum tetrachloride can be prepared from by dechlorination of

molybdenum pentachloride Molybdenum(V) chloride is the inorganic compound with the empirical formula . This dark volatile solid is used in research to prepare other molybdenum compounds. It is moisture-sensitive and soluble in chlorinated solvents. Structure Usually call ...

using

tetrachloroethene Tetrachloroethylene, also known under the systematic name tetrachloroethene, or perchloroethylene, and many other names (and abbreviations such as "perc" or "PERC", and "PCE"), is a chlorocarbon with the formula Cl2C=CCl2 . It is a colorless liq ...

: : 2MoCl₅ + C₂Cl₄ → 2MoCl₄ + C₂Cl₆ Heating α-molybdenum tetrachloride in a sealed container in the presence of molybdenum pentachloride induces conversion to the β polymorph.

Reactions

When heated in an open container, molybdenum tetrachloride evolves chlorine, giving

molybdenum trichloride Molybdenum(III) chloride is the inorganic compound with the formula MoCl3. It forms purple crystals. Synthesis and structure Molybdenum(III) chloride is synthesized by the reduction of molybdenum(V) chloride with hydrogen. A higher yield is prod ...

; : 2MoCl₄ → 2MoCl₃ + Cl₂ The

acetonitrile complex Transition metal nitrile complexes are coordination compounds containing nitrile ligands. Because nitriles are weakly basic, the nitrile ligands in these complexes are often labile. Scope of nitriles Typical nitrile ligands are acetonitrile, pro ...

adduct can be prepared by reduction of the pentachloride with acetonitrile: : 2MoCl₅ + 5CH₃CN → 2MoCl₄(CH₃CN)₂ + ClCH₂CN + HCl The MeCN

ligand In coordination chemistry, a ligand is an ion or molecule ( functional group) that binds to a central metal atom to form a coordination complex. The bonding with the metal generally involves formal donation of one or more of the ligand's ele ...

s can be exchanged with other ligands: : MoCl₄(CH₃CN)₂ + 2 THF → MoCl₄(THF)₂ + 2CH₃CN The pentachloride can be reduced to the

ether complex 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. Com ...

MoCl₄(Et₂O)₂ using tin powder. It is a beige, paramagnetic solid.

References

{{Chlorides Chlorides Molybdenum halides