Arsenic sulfide (Arsenic sulfide)

Japanese: 硫化ヒ素(硫化砒素) - りゅうかひそ（英語表記）arsenic sulfide

A general term for compounds of arsenic and sulfur. The following three types are known. Tetraarsenic trisulfide As ₄ S ₃ is also said to exist, but its existence is unclear.
[Tetraarsenic tetrasulfide]
Chemical formula: As ₄ S ₄ . It occurs naturally as realgar. It is produced by vacuum sealing equimolar amounts of arsenic and sulfur in a quartz tube, reacting them at 500°C for one hour, then at 600°C for three hours, and then slowly cooling them. At room temperature, it appears as a deep red glossy crystal called the α form, and at 267°C it transforms into black crystals called the β form. It is insoluble in water. The crystals contain As ₄ S ₄ units that form a cage structure with As atoms located at the vertices of a tetrahedron (Figure).

Source: Heibonsha World Encyclopedia, 2nd Edition Information

Japanese:

ヒ素と硫黄の化合物の総称。次にあげる3種が知られている。三硫化四ヒ素As₄S₃も存在するといわれているが明らかでない。
［四硫化四ヒ素］
　化学式As₄S₄。天然に鶏冠石として産する。ヒ素と硫黄の等モル量を石英管に真空封入して，はじめ500℃で1時間，ついで600℃で3時間反応させてから徐冷してつくる。常温では深紅色光沢ある結晶でα形と呼ばれ，267℃で黒色の結晶，β形に転移する。水に不溶。結晶中ではAs原子が四面体の頂点に位置したかご形構造をとるAs₄S₄単位を含んでいる(図)。

出典　株式会社平凡社世界大百科事典第２版について　情報

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