Electron density distribution studies on cubic BN,TiB2 and boron carbide B13C2

On the 3 compounds electron density distribution studies from accurate X‐ray diffraction data have been performed leading to valence and deformation density maps and revealing the bonding features. In BN we have a formal charge transfer of 0.44 el. from B to N in agreement with theory. In TiB2 we observe sp2 hybridisation in the boron layers and additional bonding between the boron layers along the c‐axis. Further studies on boron carbide show no charge transfer from the C‐B‐C chain to the icosahedron.