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摘要
In this perspective article we describe recent infrared spectroscopic investigations of mass-selected M+-H-2 and M+-D-2 complexes in the gas-phase, with targets that include Li+-H-2, B+-H-2, Na+-H-2, Mg+-H-2, Al+-H-2, Cr+-D-2, Mn+-H-2, Zn+-D-2 and Ag+-H-2. Interactions between molecular hydrogen and metal cations play a key role in several contexts, including in the storage of molecular hydrogen in zeolites, metal-organic frameworks, and doped carbon nanostructures. Arguably, the clearest view of the interaction between dihydrogen and a metal cation can be obtained by probing M+-H-2 complexes in the gas phase, free from the complicating influences of solvents or substrates. Infrared spectra of the complexes in the H-H and D-D stretch regions are obtained by monitoring M+ photofragments as the excitation wavelength is scanned. The spectra, which feature full rotational resolution, confirm that the M+-H-2 complexes share a common T-shaped equilibrium structure, consisting essentially of a perturbed H-2 molecule attached to the metal cation, but that the structural and vibrational parameters vary over a considerable range, depending on the size and electronic structure of the metal cation. Correlations are established between intermolecular bond lengths, dissociation energies, and frequency shifts of the H-H stretch vibrational mode. Ultimately, the M+-H-2 and M+-D-2 infrared spectra provide a comprehensive set of benchmarks for modelling and understanding the M+center dot center dot center dot H-2 interaction.
- 出版日期2012
