While metal superhydrides can form with a number of rare earth metals under high hydrogen pressures, they are a rarity amongst the group V–XII transition metals. In fact, only the iron hydride FeH₅ has been reported to date.

Recently, a research team at the Centre for Science at Extreme Conditions synthesised the second transition metal superhydride, MnH₇, at pressures above 118 GPa. X-ray diffraction and electrical resistance measurements were accompanied by density functional theory calculations, which helped determine the number and location of hydrogen atoms within the full crystal structure.

Surprisingly, the crystal structure of MnH₇ turned out to be completely different from those predicted previously. This result can be explained by the effect of the zero-point energy, which is related to the average phonon vibrational frequency. In MnH₇, including zero-point energy in the calculations changes the most stable phase from having the previously predicted structure, which features hydrogen molecules, to the experimentally determined structure, which contains hydrogen atoms instead. This suggests that the new superhydride MnH₇ forms only because of the quantum nature of the hydrogen atom and its single-proton nucleus.