The variation of quadratic elongation vs. bond angle variance and of these two parameters as a function of NH3 penetration is reported in Figure , SI. As a general trend, lead-containing systems show smaller values of quadratic elongation and of the distortion index for the same organic cation, and slightly higher values of the bond angle variance. For comparison, the D value for (R-ClMBA)2SnI4 and (S-ClMBA)2SnI4 is about half of that reported by Lu and co-workers for (R-MBA)2SnI4 and (S-MBA)2SnI4, namely ~0.004 and ~0.008, respectively. On the other hand, by keeping the same central metal (Pb or Sn) and moving from MBA to ClMBA, a general reduction of the distortion index and of the quadratic elongation is observed. However, we realize that the number of chiral 2D perovskites (with solved crystal structure) available and suitable to extract more solid structural correlations is limited. Still, we may, with these preliminary results, suggest a possible route to tune the distortion parameters.