Binding of molecular hydrogen to halide anions: A computational exploration of eco-friendly materials for hydrogen storage

Sumanene: an efficient π-bowl for dihydrogen storage

The outstanding ability of sumanene, its anionic and dianionic forms and sumanene–M⁺ion-pair complexes (M = Li, Na, K) to bind dihydrogen has been revealed using density functional theory calculations pointing out that these systems could be employed for developing new H₂storage systems.

Dihydrogen Binding Affinity of Polyatomic Anions: A DFT Study

The dihydrogen-binding ability of polyatomic oxohalo anions ClO^-, ClO₂ ^-, ClO₃ ^-, ClO₄ ^-, BrO^-, BrO₂ ^-, BrO₃ ^-, and BrO₄ ^- has been studied at the M06L/6-311++G(d,p) density functional theory and the CCSD(T)/aug-cc-pVTZ//CCSD/aug-cc-pVDZ ab initio theory. The maximum number of dihydrogen adsorbed by the anions (n _max) varies from 17 to 24 in the first coordination shell. As the number of H₂ adsorbed varies from 1 to n _max, the oxochloro and oxobromo anions show a wide range for interaction energy (E _int), namely, 1.5-45.4 kcal/mol for the former and 1.4-46.0 kcal/mol for the latter. These results indicate that both series of anions show very similar and high affinity to bind with several dihydrogen molecules. Further, an increase in the coordination ability and a decrease in the strength of the dihydrogen interaction are observed with an increase in the number of oxygen atoms in the polyatomic anion. In contrast, the neutral oxohaloacids show negligible interaction with dihydrogen. The anion···H₂ noncovalent interactions along with H···H dihydrogen interactions within the complex are ascertained by locating the bond critical points (bcps) in the quantum theory of atoms in molecules analysis. The electron density at the bcp summed up for all of the anion···H₂ interactions (∑ρ_bcp) showed a strong linear relationship with E _int, indicating that the stability of the complex is due to the formation of a large network of noncovalent bonds in the complex. The amount of electron density donated by the anion to the dihydrogen during complex formation is also gauged from the molecular electrostatic potential values at the nuclei (V _n) of all of the atoms in the anion. The hydrogen uptake leads to a significant reduction in the negative character of V _n, and the total change in V _n from all of the anion atoms (∑ΔV _n) is found to be directly proportional to E _int. The polyatomic anions have a very high affinity toward dihydrogen binding, which can be utilized for the development of new hydrogen storage systems.

Massive dihydrogen uptake by anionic carbon chains

The remarkable capacity of anionic and dianionic carbon chains to bind dihydrogen compared to their neutral moieties has been established theoretically and these one dimensional anions could be utilized in developing novel H₂ storage materials.

The remarkable ability of anions to bind dihydrogen

Anions show a noteworthy ability to bind with a large number of hydrogen molecules which can be utilized for the development of novel salt systems for hydrogen storage.