Within the B-C-N ternary system, the research works on novel phases isoelectronic with diamond (cf. and therein cited works) were mainly based on calculations within the quantum mechanics framework of the Density Functional Theory (DFT) , often preceding and helping synthesis efforts. Based on DFT and crystal chemistry rationale, we recently proposed a novel body-centered tetragonal (BCT) tet-C 4 as the simplest 'seed' of corner sharing carbon tetrahedra C4s, with the purpose of modeling large diamond builds (Fig. . Space group I-4m2, N° 119) . In view of recent gain of interest in large structures of superhard carbon allotropes such as orthorhombic C 16 and C 24 , and the presented context, the purpose of this work was to present crystal structure and physical properties of a novel extended carbon network of corner sharing tetrahedra derived from BCT C 4 ; namely, tetragonal C 16 (cf. Fig. , Table . Space group P-4m2, N° 115). In a second step tetragonal C 16 was used as template to construct and characterize novel binary compounds: tetragonal B 8 N 8 (Fig. ) and tetragonal C 6 N 8 (Fig. ), all shown to have close mechanical (elastic constants) and dynamical (phonon band structure) properties, as well as electronic structure with large band gaps, similar to diamond.