Interestingly, the c-axis is always longer for the (CnH2n+1NH3)2PbBr4 series, notwithstanding a smaller ionic radius of bromide ion with respect to iodide, and an average size of the inorganic slab of about 6.5 Å for lead iodide perovskites and of about 6 Å for the lead bromides (as determined from the available crystal structures). However, such an effect has been already observed in other series of 2D perovskites where, moving from the iodide to the bromide ion, by keeping the same ligand, leads to an expansion of the long axis (of about 5-6 Å, depending on the amine) as a result of a change in the staggering of the organic cations, which move apart from the halides, thus reducing the tilting of the organic cations. The origin of this effect is mostly related to the strength of the hydrogen bonding of the protonated amine with the apical halides which is well known and discussed in many recent papers. Further insight into the structural properties of the two series of 2D perovskites has been obtained by RT micro-Raman experiments. The RT Raman spectra of the (CnH2n+1NH3)2PbI4 and (CnH2n+1NH3)2PbBr4 systems (n= 6, 8, 10, 12, 14 and 16) are reported in Figures and, respectively. We limited our observation to the low energy part of the spectrum, in the region between 40-240 cm -1 . the organic cations play at least an indirect role in particular for the modes above 100 cm -1 . The Raman yield is directly associated to the organic bonds, i.e. C-C and C-N stretching modes, since CHn and (NH3) + groups modes are detected above 700 cm -1 . For both systems intense Raman features are observed between 60 and 140 cm -1 . For (CnH2n+1NH3)2PbI4, four