五氟化磷
Multi tool use五氟化磷
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IUPAC名
phosphorus pentafluoride
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别名
| 氟化磷（V）
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识别
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CAS号
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7647-19-0  |
PubChem
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24295
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ChemSpider
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22715
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SMILES
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InChI
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InChIKey
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OBCUTHMOOONNBS-UHFFFAOYAH
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UN编号
| 2198
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EINECS
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231-602-3
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RTECS
| TH4070000
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性质
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化学式
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PF5
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摩尔质量
| 125.9685 g·mol⁻¹
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外观
| 無色氣體
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熔点
| −93.78 °C (179.4 K)
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沸点
| −84.5 °C (188.7 K)
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溶解性（水）
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水解
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结构
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分子构型
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三角双锥
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偶极矩
| 0 D
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相关物质
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其他阴离子
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PF3
PCl5 |
相关五氟化物
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SbF5, ClF5, BrF5, IF5, TaF5, UF5 |
相关化学品
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VOF3 |
若非注明，所有数据均出自一般条件（25 ℃，100 kPa）下。
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五氟化磷（化学式：PF5），是磷鹵化合物，磷原子的氧化數為+5，包含有一个三中心四电子键。[1]
五氟化磷在常溫常壓下為無色惡臭氣體，其對皮膚、眼睛、粘膜有強烈刺激性。是活性極大的化合物，在潮濕空氣中會劇烈產生有毒和腐蝕性的氟化氫白色煙霧。五氟化磷被用作聚合反應的催化劑。
結構
五氟化磷分子为三角双锥构型，单晶X射线衍射研究顯示PF5分子有兩種不同的P−F鍵（垂直與水平）：P−Fax = 158.0 pm 與 P−Feq = 152.2 pm。氣相電子衍射分析也得到相似的值：P−Fax = 158 pm 與P−Feq = 153 pm。
有趣的是，即使在−100°C 的低温下，19F核磁共振譜也无法分辨轴向的氟原子与水平面的氟原子，只有一个简单的氟共振峰；这表明在毫秒单位级时，五氟化磷的五个氟原子是等同的，轴向与水平方向的氟原子发生着极快的交换作用。電子衍射和单晶X射线衍射沒有發現這種影響，是因为他們的時間單位比核磁共振譜學更短，从而得以分辨出两种不同的氟原子。
这个现象首先由 Gutowsky[2] 注意到，目前一般通过Berry假旋转作用来解释，即认为两个三角双锥结构通过变为一个四方锥构型的中间体，在不停地发生着转换。
参见
- 其他磷的卤化物：五氯化磷、五溴化磷、五碘化磷；三氟化磷
- 氟磷酸
参考资料
^ Greenwood, N. N.; Earnshaw, A. (1997). Chemistry of the Elements, 2nd Edition, Oxford:Butterworth-Heinemann. ISBN 0-7506-3365-4.
^ Gutowsky, H. S.; McCall, D. W.; Slichter, C. P. "Nuclear Magnetic Resonance Multiplets in Liquids" Journal of Chemical Physics 1953, volume 21, 279.
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