In this context of special tetrahedral structural features, we were interested in proposing binary systems with edge-and corner-sharing tetrahedra. For this purpose, the crystal symmetry was redefined in a primitive space group P4 2 /mnm (No. 136) with two 4-fold Wyckoff positions, which is also identified with the crb topology. Fig. displays the two alternating carbon sites, represented by brown and white spheres, with the structural parameters provided in Table , which shows the same interatomic distances and cell volume (cf. Table ) during the transformation from