All in all, we consider that both BaZnSb2 and B2H6 mark the extremes of ET values (0 and 0.63) in the green region of Fig. that covers MMBs. The ET= 0 value for Sb-Sb bonds in BaZnSb2 is a consequence of all Sb atoms in the plane array having the same electric charge (see Fig. ), which in turn is related to the translational symmetry since all Sb atoms in the planar array are equivalent (occupy the same Wyckoff 4c site) . It must be stressed that the presence of EDMBs in Zintl phases, intermetallic compounds, and cluster compounds (with homonuclear bonds) of maingroup elements is consistent with the well-known brittle and shiny metallic properties attributed to them . Note that EDMBs bonds are directional bonds, due to the existence of partially localized electrons which lead to brittle behavior, and have delocalized electrons, thus leading to a shiny metallic aspect, as expected for incipient metals.