Molybdenum Sulfide - Leucamolybdenum

Known forms include MoS ₂ , MoS ₃ , MoS ₄ , Mo ₂ S ₃ , Mo ₂ S ₅ , and Mo ₃ S _4. [ I ] Molybdenum disulfide: MoS ₂ (160.072). It exists naturally as molybdenumite. It can be obtained by directly reacting molybdenum with a calculated amount of sulfur, by heating MoS ₃ in H ₂ S, or by melting MoS ₃ in a mixture of sulfur and potassium carbonate. It appears as a black powder or hexagonal crystals. Its density is 5.06 g cm ^-3 . Its melting point is 1185 °C. It is a semiconductor, diamagnetic, and the most stable sulfide at high temperatures. It dissolves in aqua regia and boiling concentrated sulfuric acid, but is not affected by non-oxidizing acids or ammonia. It has a triangular prism structure with six S atoms at the vertices, and structures incorporating Mo atoms are connected to form a layered lattice. The layers are slippery, and it exhibits mechanical properties similar to those of graphite. A high-temperature lubricant, commonly used in automobile engine oils, gear oils, and greases. Also important in the petroleum industry as a hydrodesulfurization catalyst. [CAS 1317-33-5] [ II ] Molybdenum trisulfide: MoS ₃ (192.1). Black solid. Precipitates when H ₂ S is passed through a weakly acidic solution of molybdate. Brown powder. Insoluble in water. Dissolves when digested in an alkaline sulfide solution to form reddish-brown thiomolybdate. [CAS 12033-29-3] [ III ] Dimolybdenum trisulfide: Mo ₂ S ₃ (288.078). Melting point 1807 °C, boiling point 1867 °C. Density 5.91 g cm ^-3 . [CAS 12033-33-9] [ IV ] Dimolybdenum pentasulfide: When a sulfuric acid solution of _{Mo2S5 and} ^MoV is reduced with zinc and passed through _H2S , _Mo2S3 precipitates, and when this is heated in a _CO2 stream, _Mo2S5 powder is obtained, but _it is highly susceptible to oxidation and cannot be separated reliably. _[ CAS 12033-34-0]

Other examples include molybdenum tetrasulfide MoS ₄ [CAS 12136-77-5] and trimolybdenum tetrasulfide Mo ₃ S ₄ [CAS 39432-48-9]. "Molybdenum and its compounds" are classified as Class 1 designated chemical substances under the PRTR Law, with oral chronic toxicity Class 3, and as hazardous substances requiring notification of their names, etc. under the Industrial Safety and Health Law (disclosure of names, etc.).

Source: Morikita Publishing "Chemical Dictionary (2nd Edition)" Information about the Chemical Dictionary 2nd Edition

MoS₂，MoS₃，MoS₄，Mo₂S₃，Mo₂S₅，Mo₃S₄などが知られている．【Ⅰ】二硫化モリブデン：MoS₂(160.072)．天然に輝水鉛鉱として存在する．モリブデンと計算量の硫黄の直接反応，MoS₃をH₂S中で加熱，またはMoS₃を硫黄と炭酸カリウムの混合物で融解すると得られる．黒色粉末または六方晶系の結晶．密度5.06 g cm^－3．融点1185 ℃．半導体，反磁性，高温でもっとも安定な硫化物．王水，沸騰した濃硫酸には溶けるが，酸化力のない酸，アンモニアには侵されない．6個のS原子を頂点とする三角柱型構造のなかに，Mo原子を取り込んだ構造が連なって層状格子をつくっていて，層がすべりやすく，グラファイト(黒鉛)のような機械的性質を示す．高温用潤滑剤で，自動車用エンジンオイル，ギヤオイル，グリースなどに多用される．水素化脱硫触媒として石油産業でも重要である．[CAS 1317-33-5]【Ⅱ】三硫化モリブデン：MoS₃(192.1)．黒色の固体．モリブデン酸塩の弱酸性溶液にH₂Sを通じると沈殿する．褐色の粉末．水に不溶．硫化アルカリ溶液で温浸すると溶けて，赤褐色のチオモリブデン酸塩となる．[CAS 12033-29-3]【Ⅲ】三硫化二モリブデン：Mo₂S₃(288.078)．融点1807 ℃，沸点1867 ℃．密度5.91 g cm^－3．[CAS 12033-33-9]【Ⅳ】五硫化二モリブデン：Mo₂S₅，Mo^Ⅴの硫酸酸性溶液を亜鉛で還元し，H₂Sを通じるとMo₂S₃の沈殿が生じ，これをCO₂気流中で熱するとMo₂S₅粉末が得られるとされているが，きわめて酸化されやすく確実には分離されてはいない．[CAS 12033-34-0]

このほか，四硫化モリブデンMoS₄[CAS 12136-77-5]，四硫化三モリブデンMo₃S₄[CAS 39432-48-9]などがある．「モリブデン及びその化合物」としてPRTR法・第一種指定化学物質 経口慢性毒性クラス3，労働安全衛生法〔名称等表示〕名称等を通知すべき有害物．

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