Hydrohelium(1+) ion
 |
|
 |
|
| Names | |
|---|---|
|
Systematic IUPAC name
Hydridohelium(1+)
|
|
| Identifiers | |
|
3D model (JSmol)
|
|
| ChEBI | |
| ChemSpider | |
| 2 | |
|
|
|
|
| Properties | |
| HeH+ |
|
| Molar mass | 5.01 g·mol−1 |
|
Except where otherwise noted, data are given for materials in their standard state (at 25 °C [77 °F], 100 kPa).
|
|
| Infobox references | |
The hydrohelium(1+) cation, HeH+, also known as the helium hydride ion or helium-hydride molecular ion, is a positively charged ion formed by the reaction of a proton with a helium atom in the gas phase, first produced in the laboratory in 1925. It is isoelectronic with molecular hydrogen. It is the strongest known acid, with a proton affinity of 177.8 kJ/mol. It has been suggested that HeH+ should occur naturally in the interstellar medium, but it has not yet been detected. It is the simplest heteronuclear ion, and is comparable with the hydrogen molecular ion, H+
2. Unlike H+
2, however, it has a permanent dipole moment, which makes its spectroscopic characterization easier. The calculated dipole moment of HeH+ is 2.26 or 2.84.
HHe+ cannot be prepared in a condensed phase, as it would protonate any anion, molecule or atom with which it were associated. However it is possible to estimate a hypothetical aqueous acidity using Hess's law:
...
Wikipedia