氦合氢离子
氦合氢离子 | |
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系统名 Hydridohelium(1+)[1] | |
识别 | |
CAS号 | 17009-49-3 ![]() |
ChemSpider | 21106447 |
SMILES |
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Gmelin | 2 |
ChEBI | 33688 |
性质 | |
化学式 | HeH+ |
摩尔质量 | 5.01054 g·mol⁻¹ |
若非注明,所有数据均出自标准状态(25 ℃,100 kPa)下。 |
氦合氢离子,又称氦氢分子离子,化学式为HeH+,是一种带正电的离子。它首次发现于1925年,通过质子(或氢离子)和氦原子在气相中反应制得。[2]氦合氢离子是已知最强的布朗斯特质子酸,质子亲和能为177.8 kJ/mol。[3]有人认为,这种物质可以存在于自然星际物质中。[4]氦合氢离子是最简单的异核离子,可以与同核的氢分子离子H2+相比较。与H2+不同的是,它有一个永久的键偶极矩,因此更容易表现出光谱特征。[5]《自然》杂志于2019年发表的研究显示,人类首次在太空中检测到了氦合氢离子。[6]
性质
HHe+不能在凝聚相中制备,因为在凝聚态中它会与所有的阴离子、分子或是原子发生作用。它可以使O2、NH3、SO2、H2O和CO2质子化,分别形成O2H+、NH+
4、HSO+
2、H3O+和 HCO+
2[7]。诸如一氧化氮、二氧化氮、一氧化二氮、硫化氢、甲烷、乙炔、乙烯、乙烷、甲醇和乙腈等分子也会与之反应,不过产物会因为能量太高而直接分解。[7]但是,可以用盖斯定律预测它在水溶液中的酸性:
HHe+(g) | → | H+(g) | + He(g) | +178 kJ/mol | [3] |
HHe+(aq) | → | HHe+(g) | +973 kJ/mol | [8] | |
H+(g) | → | H+(aq) | – 1530 kJ/mol | ||
He(g) | → | He(aq) | +19 kJ/mol | [9] | |
HHe+(aq) | → | H+(aq) | + He(aq) | – 360 kJ/mol |
电离过程–360 kJ/mol的自由能变化相当于pKa为-63。
其他的氦氢化物离子均已知或者已在理论上进行了研究。HeH2+已经能被微波光谱观测到,[11]经计算,它的亲和能为6 kcal/mol,而HeH3+的亲和能为0.1 kcal/mol。[12]
中性分子
不同于氦合氢离子,氢和氦构成的中性分子在一般情况下很不稳定。但是,它作为一个准分子在激发态时是稳定的,于20世纪80年代中期首次在光谱中观测到。[13][14][15]
参考文献
引用
- ^ hydridohelium(1+) (CHEBI:33688). Chemical Entities of Biological Interest (ChEBI). UK: European Bioinformatics Institute. [2012-03-13]. (原始内容存档于2019-04-19).
- ^ T. R. Hogness and E. G. Lunn. The Ionization of Hydrogen by Electron Impact as Interpreted by Positive Ray Analysis. Physical Review. 1925, 26: 44–55. doi:10.1103/PhysRev.26.44.
- ^ 3.0 3.1 Lias, S. G.; Liebman, J. F.; Levin, R. D. Evaluated Gas Phase Basicities and Proton Affinities of Molecules; Heats of Formation of Protonated Molecules. Journal of Physical and Chemical Reference Data. 1984, 13: 695. doi:10.1063/1.555719.
- ^ J. Fernandez; F. Martin. Photoionization of the HeH+ molecular ion. J. Phys. B: At. Mol. Opt. Phys. 2007, 40: 2471–2480. doi:10.1088/0953-4075/40/12/020.
- ^ Coxon, J; Hajigeorgiou, PG. Experimental Born–Oppenheimer Potential for theX1Σ+Ground State of HeH+: Comparison with theAb InitioPotential. Journal of Molecular Spectroscopy. 1999, 193 (2): 306. PMID 9920707. doi:10.1006/jmsp.1998.7740.
- ^ Stutzki, Jürgen; Risacher, Christophe; Ricken, Oliver; Klein, Bernd; Karl Jacobs; Graf, Urs U.; Menten, Karl M.; Neufeld, David; Wiesemeyer, Helmut. Astrophysical detection of the helium hydride ion HeH +. Nature. 2019-04, 568 (7752): 357–359 [2019-04-18]. ISSN 1476-4687. doi:10.1038/s41586-019-1090-x. (原始内容存档于2019-04-18) (英语).
- ^ 7.0 7.1 Grandinetti, Felice. Helium chemistry: a survey of the role of the ionic species. International Journal of Mass Spectrometry. October 2004, 237 (2–3): 243–267. Bibcode:2004IJMSp.237..243G. doi:10.1016/j.ijms.2004.07.012.
- ^ Estimated to be the same as for Li+(aq) → Li+(g).
- ^ Estimated from solubility data.
- ^ Coyne, John P.; Ball, David W. Alpha particle chemistry. On the formation of stable complexes between He2+ and other simple species: implications for atmospheric and interstellar chemistry. Journal of Molecular Modeling. 2009, 15 (1): 37. PMID 18936986. doi:10.1007/s00894-008-0371-3.
- ^ Alan Carrington, David I. Gammie, Andrew M. Shaw, Susie M. Taylor and Jeremy M. Hutson. Observation of a microwave spectrum of the long-range He···H2+ complex. Chemical Physics Letters. 1996, 260: 395–405. doi:10.1016/0009-2614(96)00860-3.
- ^ F.Pauzat and Y. Ellinger Where do noble gases hide in space? 互联网档案馆的存檔,存档日期2007-02-02., Astrochemistry: Recent Successes and Current Challenges, Poster Book IAU Symposium No. 231, 2005 A. J. Markwick-Kemper (ed.)
- ^ Thomas Möller, Michael Beland, and Georg Zimmerer. Observation of Fluorescence of the HeH Molecule. Phys. Rev. Lett. 1985, 55 (20): 2145–2148. PMID 10032060. doi:10.1103/PhysRevLett.55.2145.
- ^ Wolfgang Ketterle. Nobel Prizes. (原始内容存档于2010-12-14).
- ^ W. Ketterle, H. Figger, and H. Walther. Emission spectra of bound helium hydride. Phys. Rev. Lett. 1985, 55 (27): 2941–2944. PMID 10032281. doi:10.1103/PhysRevLett.55.2941.
来源
- 除非另外提及,数据取自Weast, R. C. (Ed.) (1981). CRC Handbook of Chemistry and Physics (62nd Edn.). Boca Raton, FL: CRC Press. ISBN 0-8493-0462-8.
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