Novel Pressure-Induced Interactions in Silane-Hydrogen

We report novel molecular compound formation from silane-hydrogen mixtures with intermolecular interactions unprecedented for hydrogen-rich solids. A complex ${\mathrm{H}}_{2}$ vibron spectrum with anticorrelated pressure-frequency dependencies and a striking H-D exchange below 10 GPa reveal strong and unusual attractive interactions between ${\mathrm{SiH}}_{4}$ and ${\mathrm{H}}_{2}$ and molecular bond destabilization at remarkably low pressure. The unique features of the observed ${\mathrm{SiH}}_{4}({\mathrm{H}}_{2}{)}_{2}$ compound suggest a new range of accessible pressure-driven intermolecular interactions for hydrogen-bearing simple molecular systems and a new approach to perturb the hydrogen covalent bond.