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高氙酸盐
	IUPAC名; Hexaoxoxenonate(4-)
英文名	Perxenate
识别
CAS号	12340-17-9
性质
化学式	XeO64−
摩尔质量	227.29 g·mol⁻¹
	若非注明，所有数据均出自标准状态（25 ℃，100 kPa）下。

高氙酸盐是高氙酸（H₄Xe O₆）所成的盐，含有黄色^[1]的高氙酸根离子——XeO₆⁴⁻。^[2]由拉曼光谱确定这种阴离子为八面体形分子构型, O–Xe–O 键角在87°至 93°之间。^[3] 其中的Xe–O键长已通过X射线晶体学确认，为 1.875 Å。^[4]

制备

高氙酸盐是通过三氧化氙在强碱中歧化而成的：^[5]

2 XeO₃ (s) + 4 OH⁻ (aq) → Xe (g) + XeO4−
6 (aq) + O₂ (g) + 2 H₂O (l)

当其中的碱是Ba(OH)₂ 时，可以在溶液中得到高氙酸钡晶体。^[5]

高氙酸

高氙酸是高氙酸根不稳定的共轭酸，由四氧化氙在水中形成。它没有作为游离酸被分离出来，因为在酸性条件下它会迅速分解成三氧化氙和氧气：^[6]^[7]

2 HXeO3−
6 + 6 H+
→ 2 XeO
3 + 4 H
2O + O
2

高氙酸的pK_a 已间接计算，数值低于0，使其成为极强的酸。它的第一次去质子化会产生 H
3XeO−
6， pK_a 为 4.29，仍然相对的酸。两次去质子化物种 H
2XeO2−
6 的 pK_a 为 10.81。^[8] 然而，由于高氙酸在如上所述的酸性条件下快速分解，因此最常见的高氙酸盐带有阴离子 XeO4−
6。^[6]^[2]

性质

高氙酸和阴离子 XeO4−
6 都是强氧化剂，^[9]可以把银(I)氧化成银(III)，把铜(II)氧化成铜(III)，^[10]以及把锰(II)氧化成高锰酸盐。^[11]高氙酸盐在酸性环境下不稳定，^[10]会立刻被还原成 HXeO−
4。^[1]

高氙酸的钠、钾和钡盐可溶。^[12] 高氙酸钡溶液是合成四氧化氙 (XeO₄) 的起始材料，方法是将其与浓硫酸混合：^[13]

Ba₂XeO₆ (s) + 2 H₂SO₄ (l) → XeO₄ (g) + 2 BaSO₄ (s) + 2 H₂O (l)

大部分金属的高氙酸盐稳定，会剧烈分解的高氙酸银除外。^[10]

应用

高氙酸钠 Na₄XeO₆可用来在锔中分离微量的镅。在酸性溶液和La³⁺存在下，用高氙酸钠把 Am³⁺ 氧化成Am⁴⁺，然后用氟化钙处理，产生 Cm³⁺ 和La³⁺的不溶氟化物，但 Am⁴⁺ 和Pu⁴⁺ 的氟化物可溶，会留在溶液中。^[9]

参考资料

^ ^1.0 ^1.1 Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred, Advanced Inorganic Chemistry 6th, New York: Wiley-Interscience: 593, 1999, ISBN 0-471-19957-5
^ ^2.0 ^2.1 Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter: 399, 2001, ISBN 0-12-352651-5
^ Peterson, J. L.; Claassen, H. H.; Appelman, E. H. Vibrational spectra and structures of xenate(VI) and perxenate(VIII) ions in aqueous solution. Inorganic Chemistry. March 1970, 9 (3): 619–621. doi:10.1021/ic50085a037.
^ Hamilton; Ibers, J.; MacKenzie, D. Geometry of the Perxenate Ion. Science. Aug 1963, 141 (3580): 532–534. Bibcode:1963Sci...141..532H. ISSN 0036-8075. PMID 17738629. doi:10.1126/science.141.3580.532.
^ ^5.0 ^5.1 Harding, Charlie; Johnson, David Arthur; Janes, Rob. Elements of the p Block. Molecular World 9. Royal Society of Chemistry. 2002: 93. ISBN 0-85404-690-9.
^ ^6.0 ^6.1 Klaening, U. K.; Appelman, E. H. Protolytic properties of perxenic acid. Inorganic Chemistry. October 1988, 27 (21): 3760–3762. doi:10.1021/ic00294a018.
^ Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter: 400, 2001, ISBN 0-12-352651-5
^ John H. Holloway; Eric G. Hope. A. G. Sykes , 编. Advances in Inorganic Chemistry 46. Academic Press. 1998: 67. ISBN 0-12-023646-X.
^ ^9.0 ^9.1 Holcomb, H. P. Analytical Oxidation of Americium with Sodium Perxenate. Analytical Chemistry. March 1965, 37 (3): 415. doi:10.1021/ac60222a002.
^ ^10.0 ^10.1 ^10.2 Allen J. Bard; Roger Parsons; Joseph Jordan; International Union of Pure and Applied Chemistry. Standard Potentials in Aqueous Solution. CRC Press. 1985: 778. ISBN 0-8247-7291-1.
^ Linus Pauling. General Chemistry 3rd. Courier Dover Publications. 1988: 251. ISBN 0-486-65622-5.
^ Thomas Scott; Mary Eagleson. Concise encyclopedia chemistry. Walter de Gruyter. 1994: 1183. ISBN 3-11-011451-8.
^ Charlie Harding; David Arthur Johnson; Rob Janes. Elements of the p block. Great Britain: Royal Society of Chemistry. 2002: 92–93. ISBN 0-85404-690-9.

[cotton1-1] 1.0 ^1.1 Cotton, F. Albert; Wilkinson, Geoffrey; Murillo, Carlos A.; Bochmann, Manfred, Advanced Inorganic Chemistry 6th, New York: Wiley-Interscience: 593, 1999, ISBN 0-471-19957-5

[wiberg-2] 2.0 ^2.1 Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter: 399, 2001, ISBN 0-12-352651-5

[3] Peterson, J. L.; Claassen, H. H.; Appelman, E. H. Vibrational spectra and structures of xenate(VI) and perxenate(VIII) ions in aqueous solution. Inorganic Chemistry. March 1970, 9 (3): 619–621. doi:10.1021/ic50085a037.

[hamilton1963-4] Hamilton; Ibers, J.; MacKenzie, D. Geometry of the Perxenate Ion. Science. Aug 1963, 141 (3580): 532–534. Bibcode:1963Sci...141..532H. ISSN 0036-8075. PMID 17738629. doi:10.1126/science.141.3580.532.

[harding2002-5] 5.0 ^5.1 Harding, Charlie; Johnson, David Arthur; Janes, Rob. Elements of the p Block. Molecular World 9. Royal Society of Chemistry. 2002: 93. ISBN 0-85404-690-9.

[klaening-6] 6.0 ^6.1 Klaening, U. K.; Appelman, E. H. Protolytic properties of perxenic acid. Inorganic Chemistry. October 1988, 27 (21): 3760–3762. doi:10.1021/ic00294a018.

[7] Holleman, Arnold Frederik; Wiberg, Egon, Wiberg, Nils , 编, Inorganic Chemistry, 由Eagleson, Mary; Brewer, William翻译, San Diego/Berlin: Academic Press/De Gruyter: 400, 2001, ISBN 0-12-352651-5

[8] John H. Holloway; Eric G. Hope. A. G. Sykes , 编. Advances in Inorganic Chemistry 46. Academic Press. 1998: 67. ISBN 0-12-023646-X.

[holcomb-9] 9.0 ^9.1 Holcomb, H. P. Analytical Oxidation of Americium with Sodium Perxenate. Analytical Chemistry. March 1965, 37 (3): 415. doi:10.1021/ac60222a002.

[bard1-10] 10.0 ^10.1 ^10.2 Allen J. Bard; Roger Parsons; Joseph Jordan; International Union of Pure and Applied Chemistry. Standard Potentials in Aqueous Solution. CRC Press. 1985: 778. ISBN 0-8247-7291-1.

[11] Linus Pauling. General Chemistry 3rd. Courier Dover Publications. 1988: 251. ISBN 0-486-65622-5.

[12] Thomas Scott; Mary Eagleson. Concise encyclopedia chemistry. Walter de Gruyter. 1994: 1183. ISBN 3-11-011451-8.

[13] Charlie Harding; David Arthur Johnson; Rob Janes. Elements of the p block. Great Britain: Royal Society of Chemistry. 2002: 92–93. ISBN 0-85404-690-9.

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