Porous coordination spin-crossover polymers like {Fe(pyrazine)[Pt(CN)4]} represent a remarkable class of bistable chemo-responsive materials due to the possibility of switching between the paramagnetic high-spin (HS) state and the diamagnetic low-spin (LS) state through guest adsorption processes. Given the importance of natural and anthropogenic release SO2 into the environment, and of H2 as a clean alternative to hydrocarbon fuels, we are interested in the study of the mechanisms of H2 and SO2 interaction with the host framework. We propose to study the host-guest interaction from the experimental density of states measured by means of the neutron vibrational spectrometer Lagrange. The proposed experiment is divided in two parts: (i) the study of a deuterated sample of {Fe(pz)[Pt(CN)4]} with and without SO2, at 2 different temperatures: at 287 K (bistability region) and at 10 K in order to decrease the Debye Waller factor, and (ii) the study a non-deuterated sample of {Fe(pz)[Pt(CN)4]} with and without H2, at 77 K.