氦合氢离子

(重定向自氦合氫離子

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]

氦合氢离子
系统名
Hydridohelium(1+)[1]
识别
CAS号 17009-49-3  checkY
ChemSpider 21106447
SMILES
 
  • [HeH+]
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。

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O2NH3SO2H2OCO2质子化,分别形成O2H+NH+
4
HSO+
2
H3O+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。

HeH+共价键的长度是0.772Å[10]

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

  1. ^ 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). 
  2. ^ 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. ^ 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. 
  4. ^ 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. 
  5. ^ 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. 
  6. ^ 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. ^ 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. 
  8. ^ Estimated to be the same as for Li+(aq) → Li+(g).
  9. ^ Estimated from solubility data.
  10. ^ 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. 
  11. ^ 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. 
  12. ^ F.Pauzat and Y. Ellinger Where do noble gases hide in space? 互联网档案馆存檔,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.)
  13. ^ 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. 
  14. ^ Wolfgang Ketterle. Nobel Prizes. (原始内容存档于2010-12-14). 
  15. ^ 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. 

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