The respective local boron coordinations announced above for the template structures are confirmed for the BCN models. The upper part of Table provides crystal symmetry and computed energies for all three BCN models. The atom-averaged cohesive energies were obtained after subtracting the atomic energies given in the last line of Table . The most favorable structure is the orthorhombic one presenting square planar BC2N2 coordination (Fig. ), and the least favorable is CoCN-type structure where B is hexacoordinated with BC3N3-like octahedron shown in Fig. , that is clearly excluded for boron. Linear B-C-N local arrangements in the CuCN-like BCN (Fig. ) lead to an intermediate energy situation.