Molybdenum dioxide is the

chemical compound A chemical compound is a chemical substance composed of many identical molecules (or molecular entities) containing atoms from more than one chemical element held together by chemical bonds. A molecule consisting of atoms of only one ele ...

with the formula MoO. It is a violet-colored solid and is a metallic conductor. The mineralogical form of this compound is called

tugarinovite Tugarinovite is a rare molybdenum oxide mineral with formula MoO2. It occurs as a primary mineral phase associated with metasomatism in a sulfur deficient reducing environment. In the type locality it occurs with uraninite, molybdenite, galena, ...

, and is only very rarely found.

Structure

It crystallizes in a

monoclinic In crystallography, the monoclinic crystal system is one of the seven crystal systems. A crystal system is described by three vectors. In the monoclinic system, the crystal is described by vectors of unequal lengths, as in the orthorhombic ...

cell, and has a distorted rutile, ( TiO₂) crystal structure. In TiO the oxide anions are close packed and titanium atoms occupy half of the octahedral interstices (holes). In MoO the octahedra are distorted, the Mo atoms are off-centre, leading to alternating short and long Mo – Mo distances and Mo-Mo bonding. The short Mo – Mo distance is 251 pm which is less than the Mo – Mo distance in the metal, 272.5 pm. The bond length is shorter than would be expected for a single bond. The bonding is complex and involves a

delocalisation In chemistry, delocalized electrons are electrons in a molecule, ion or solid metal that are not associated with a single atom or a covalent bond.IUPAC Gold Boo''delocalization''/ref> The term delocalization is general and can have slightly di ...

of some of the Mo electrons in a conductance band accounting for the metallic conductivity.

Preparation

MoO can be prepared : *by reduction of MoO₃ with Mo over the course of 70 hours at . The

tungsten Tungsten, or wolfram, is a chemical element with the symbol W and atomic number 74. Tungsten is a rare metal found naturally on Earth almost exclusively as compounds with other elements. It was identified as a new element in 1781 and first isol ...

analogue, WO, is prepared similarly. :2 MoO + Mo → 3 MoO *by reducing MoO with H₂ or NH₃ below Single crystals are obtained by chemical transport using

iodine Iodine is a chemical element with the Symbol (chemistry), symbol I and atomic number 53. The heaviest of the stable halogens, it exists as a semi-lustrous, non-metallic solid at standard conditions that melts to form a deep violet liquid at , ...

. Iodine reversibly converts MoO₂ into the volatile species MoOI.

Uses

Molybdenum dioxide is a constituent of "technical molybdenum trioxide" produced during the industrial processing of MoS₂: :2 MoS + 7 O → 2 MoO + 4 SO :MoS + 6 MoO → 7 MoO + 2 SO :2 MoO + O → 2 MoO MoO has been reported as catalysing the

dehydrogenation In chemistry, dehydrogenation is a chemical reaction that involves the removal of hydrogen, usually from an organic molecule. It is the reverse of hydrogenation. Dehydrogenation is important, both as a useful reaction and a serious problem. A ...

of alcohols, the reformation of hydrocarbons and biodiesel. Molybdenum nano-wires have been produced by reducing MoO deposited on graphite. Molybdenum dioxide has also been suggested as possible anode material for

Li-ion batteries A lithium-ion or Li-ion battery is a type of rechargeable battery which uses the reversible reduction of lithium ions to store energy. It is the predominant battery type used in portable consumer electronics and electric vehicles. It also sees ...

References

{{oxygen compounds molybdenum(IV) compounds transition metal oxides