SOLID-STATE BORAZINE - DOES IT DESERVE TO BE ENTITLED INORGANIC BENZENE

The molecular and solid-state structure of borazine has been determined at 115 and 160 K by single-crystal X-ray crystallography. The molecular structure has C2 symmetry with small deviations from the expected D3h symmetry. The mean value of the BN bond length is 1.429(1) angstrom and the interbond angles of the six-membered ring are 117.1(1)-degree at the boron atoms and 122.9(1)-degrees at the nitrogen atoms (mean values). Similar to benzene an unambiguous assignment of the molecular symmetry is not possible. - The crystal packing is not comparable to any known phase of benzene, and surprisingly the molecules are not stacked having coplanar rings. Instead, the molecules are found in tilted layers. No significant intermolecular interaction could be detected. The generated difference electron density maps show the typical distribution pattern for polar bonds.