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{{redirect|MoO2|the videogame|Master of Orion II: Battle at Antares{{!}}''Master of Orion II: Battle at Antares''}} |
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| verifiedrevid = 269403595 |
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| verifiedrevid = 361075238 |
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| IUPACName = Molybdenum(IV) oxide |
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| IUPACName = Molybdenum(IV) oxide |
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| OtherNames = Molybdenum dioxide<br/>] |
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| OtherNames = Molybdenum dioxide<br/>] |
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| Section1 = {{Chembox Identifiers |
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|Section1={{Chembox Identifiers |
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| CASNo = 18868-43-4 |
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| CASNo = 18868-43-4 |
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| CASNo_Ref = {{cascite}} |
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| CASNo_Ref = {{cascite|correct|CAS}} |
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| PubChem = |
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| PubChem = 29320 |
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| Section2 = {{Chembox Properties |
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|Section2={{Chembox Properties |
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| Formula = MoO<sub>2</sub> |
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| Formula = MoO<sub>2</sub> |
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| MolarMass = 127.94 g/mol |
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| MolarMass = 127.94 g/mol |
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| Appearance = brownish-violet solid |
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| Appearance = brownish-violet solid |
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| Density = 6.47 g/cm<sup>3</sup> |
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| Density = 6.47 g/cm<sup>3</sup> |
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| MeltingPt = 1100 °C decomp. |
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| MeltingPtC = 1100 |
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| MeltingPt_notes = decomposes |
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| BoilingPt = |
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| Solubility = insoluble |
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| Solubility = insoluble |
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| SolubleOther = insoluble in ]es, ], ] <br> slightly soluble in hot ] |
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| SolubleOther = insoluble in ]es, ], ] <br> slightly soluble in hot ] |
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| MagSus = +41.0·10<sup>−6</sup> cm<sup>3</sup>/mol |
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| Section3 = {{Chembox Structure |
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|Section3={{Chembox Structure |
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| CrystalStruct = Distorted ] (tetragonal) |
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| CrystalStruct = Distorted ] (monoclinic) |
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| Coordination = Octahedral (Mo<sup>IV</sup>); trigonal (O<sup>−II</sup>) |
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| SpaceGroup = |
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| Coordination = Octahedral (Mo<sup>IV</sup>); trigonal (O<sup>–II</sup>) |
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| Section4 = {{Chembox Thermochemistry |
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| Section7 = {{Chembox Hazards |
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| FlashPt = Non-flammable |
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| FlashPt = Non-flammable |
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| Section8 = {{Chembox Related |
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| OtherAnions = ] |
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| OtherCations = ]<br/>] |
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| Function = ] ]s |
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| OtherFunction_label = ] ]s |
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'''Molybdenum dioxide''' is the ] with the ] MoO{{sub|2}}. It is a violet-colored solid and is a metallic conductor. The mineralogical form of this compound is called ], and is only very rarely found. |
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'''Molybdenum dioxide''' is the ] with the ] MoO<sub>2</sub>. It is a violet-colored solid and is a metallic conductor. It crystallizes in a ] cell, and has a distorted rutile, (]) crystal structure. In TiO<sub>2</sub> the ] anions are ] and titanium atoms occupy half of the octahedral interstices (holes). In MoO<sub>2</sub> 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 ] 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 of some of the Mo electrons in a conductance band accounting for the metallic conductivity<ref>''Oxides: Solid state chemistry'' McCarroll W.H. Encyclopedia of Inorganic Chemistry Ed R. Bruce King, (1994), John Wiley & sons ISBN 0-471-93620-0 </ref>.<br /> |
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MoO<sub>2</sub> can be prepared : |
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*by reduction of ] with Mo over the course of 70 hours at 800 °C. The ] analogue, WO<sub>2</sub>, is prepared similarly. |
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:2 MoO<sub>3</sub> + Mo <nowiki>→</nowiki> 3 MoO<sub>2</sub> |
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*by reducing MoO<sub>3</sub> with ] or ] below 470°C <ref> {{Cotton&Wilkinson6th}}</ref> |
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==Structure== |
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Single crystals are obtained by ] using ]. Iodine reversibly converts MoO<sub>2</sub> into the volatile species MoO<sub>2</sub>I<sub>2</sub><ref>Conroy, L. E.; Ben-Dor, L. "Molybdenum(IV) Oxide and Tungsten(IV) Oxides Single-Crystals" Inorganic Syntheses 1995, volume 30, pp. 105–107. ISBN 0-471-30508-1</ref>. |
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It crystallizes in a ] cell, and has a distorted rutile, (]) crystal structure. In TiO{{sub|2}} the ] anions are ] and titanium atoms occupy half of the octahedral interstices (holes). In MoO{{sub|2}} 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 ] 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 ] of some of the Mo electrons in a conductance band accounting for the metallic conductivity.<ref>''Oxides: Solid state chemistry'' McCarroll W.H. Encyclopedia of Inorganic Chemistry Ed R. Bruce King, (1994), John Wiley & sons {{ISBN|0-471-93620-0}}</ref> |
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==Preparation== |
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Molybdenum oxide is a constituent of "technical molybdenum oxide" produced during the industrial processing of ]<ref> ''Metallurgical furnaces'' Jorg Grzella, Peter Sturm, Joachim Kruger, Markus A. Reuter, Carina Kogler, Thomas Probst, Ullmans Encyclopedia of Industrial Chemistry </ref>: |
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MoO{{sub|2}} can be prepared : |
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*by reduction of ] with Mo over the course of 70 hours at {{convert|800|C}}. The ] analogue, WO{{sub|2}}, is prepared similarly. |
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:2 MoO{{sub|3}} + Mo → 3 MoO{{sub|2}} |
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*by reducing MoO{{sub|3}} with ] or ] below {{convert|470|C}} <ref>{{Cotton&Wilkinson6th}}</ref> |
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Single crystals are obtained by ] using ]. Iodine reversibly converts MoO<sub>2</sub> into the volatile species MoO{{sub|2}}I{{sub|2}}.<ref>Conroy, L. E.; Ben-Dor, L. "Molybdenum(IV) Oxide and Tungsten(IV) Oxides Single-Crystals" Inorganic Syntheses 1995, volume 30, pp. 105–107. {{ISBN|0-471-30508-1}}</ref> |
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:2 MoS<sub>2</sub> + 7O<sub>2</sub> <nowiki>→</nowiki> 2MoO<sub>3</sub> + 4SO<sub>2</sub> |
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:MoS<sub>2</sub> + 6MoO<sub>3</sub> <nowiki>→</nowiki> 7MoO<sub>2</sub> + 2SO<sub>2</sub> |
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:2 MoO<sub>2</sub> + O<sub>2</sub> <nowiki>→</nowiki> 2MoO<sub>3</sub> |
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==Uses== |
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MoO<sub>2</sub> has been reported as catalysing the dehydrogenation of alcohols<ref>A. A. Balandin and I. D. Rozhdestvenskaya, Russian Chemical Bulletin, 8, 11, (1959), 1573 {{doi|10.1007/BF00914749 }}</ref> and the reformation of hydrocarbons<ref>''Molybdenum based catalysts. I. MoO<sub>2</sub> as the active species in the reforming of hydrocarbons'' A. Katrib, P. Leflaive, L. Hilaire and G. Maire Catalysis Letters, 38, 1–2, (1996) {{doi|10.1007/BF00806906}}</ref>. Molybdenum nano-wires have been produced by reducing MoO<sub>2</sub> deposited on graphite<ref>''Synthesis of Molybdenum Nanowires with Millimeter-Scale Lengths Using Electrochemical Step Edge Decoration'' M. P. Zach, K. Inazu, K. H. Ng, J. C. Hemminger, and R. M. Penner Chem. Mater. (2002),14, 3206 {{doi|10.1021/cm020249a}}</ref> |
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Molybdenum dioxide is a constituent of "technical molybdenum trioxide" produced during the industrial processing of ]:<ref>''Metallurgical furnaces'' Jorg Grzella, Peter Sturm, Joachim Kruger, Markus A. Reuter, Carina Kogler, Thomas Probst, Ullmans Encyclopedia of Industrial Chemistry</ref><ref>"Thermal Analysis and Kinetics of Oxidation of Molybdenum Sulfides" Y. Shigegaki, S.K. Basu, M.Wakihara and M. Taniguchi, J. Therm. Analysis 34 (1988), 1427-1440</ref> |
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:2 MoS{{sub|2}} + 7 O{{sub|2}} → 2 MoO{{sub|3}} + 4 SO{{sub|2}} |
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Mineralogical form of this compound is called ], only very rarely found. |
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:MoS{{sub|2}} + 6 MoO{{sub|3}} → 7 MoO{{sub|2}} + 2 SO{{sub|2}} |
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:2 MoO{{sub|2}} + O{{sub|2}} → 2 MoO{{sub|3}} |
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MoO{{sub|2}} has been reported as catalysing the ] of alcohols,<ref>A. A. Balandin and I. D. Rozhdestvenskaya, Russian Chemical Bulletin, 8, 11, (1959), 1573 {{doi|10.1007/BF00914749 }}</ref> the reformation of hydrocarbons<ref>''Molybdenum based catalysts. I. MoO{{sub|2}} as the active species in the reforming of hydrocarbons'' A. Katrib, P. Leflaive, L. Hilaire and G. Maire Catalysis Letters, 38, 1–2, (1996) {{doi|10.1007/BF00806906}}</ref> and biodiesel.<ref>Catalytic partial oxidation of a biodiesel surrogate over molybdenum dioxide, C.M. Cuba-Torres, et al, Fuel (2015), {{doi|10.1016/j.fuel.2015.01.003}}</ref> Molybdenum nano-wires have been produced by reducing MoO{{sub|2}} deposited on graphite.<ref>''Synthesis of Molybdenum Nanowires with Millimeter-Scale Lengths Using Electrochemical Step Edge Decoration'' M. P. Zach, K. Inazu, K. H. Ng, J. C. Hemminger, and R. M. Penner Chem. Mater. (2002),14, 3206 {{doi|10.1021/cm020249a}}</ref> Molybdenum dioxide has also been suggested as possible anode material for ].<ref>{{Cite journal|last1=Shi|first1=Yifeng|last2=Guo|first2=Bingkun|last3=Corr|first3=Serena A.|last4=Shi|first4=Qihui|last5=Hu|first5=Yong-Sheng|last6=Heier|first6=Kevin R.|last7=Chen|first7=Liquan|last8=Seshadri|first8=Ram|last9=Stucky|first9=Galen D.|date=2009-12-09|title=Ordered Mesoporous Metallic MoO2 Materials with Highly Reversible Lithium Storage Capacity|journal=Nano Letters|volume=9|issue=12|pages=4215–4220|doi=10.1021/nl902423a|pmid=19775084|issn=1530-6984}}</ref><ref>{{Cite journal|last1=Kim|first1=Hyung-Seok|last2=Cook|first2=John B.|last3=Tolbert|first3=Sarah H.|last4=Dunn|first4=Bruce|date=2015-01-01|title=The Development of Pseudocapacitive Properties in Nanosized-MoO2|journal=Journal of the Electrochemical Society|language=en|volume=162|issue=5|pages=A5083–A5090|doi=10.1149/2.0141505jes|osti=1370243|issn=0013-4651|url=https://www.osti.gov/biblio/1370243}}</ref> |
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==References== |
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==References== |
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{{Molybdenum compounds}} |
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{{Molybdenum compounds}} |
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{{oxygen compounds}} |
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