We request 3 days on TOSCA to study molecular rotations of NH4+ and BH4- ions and the ionic disorder in ammonium borohydride (rock salt lattice) and its methylated derivative. This potential hydrogen storage material is methylated in order to increase its thermodynamic stability, and we wish to investigate the effect of methylation on the disorder and lattice dynamics through inelastic neutron scattering, complementing our planned neutron diffraction and muon experiments on these materials. We will also analyse the related material methylamine borane and the decomposition product, dimethylammoniate of diborane, for comparison of the molecular rigidity in the lattice introduced by methylation.