Crystal Structure of Bis(triethylammonium)closo-decahydrodecaborate, [(C2H5)3NH]2[B10H10]
The crystal structure of bis(triethylammonium)closo-decahydrodecaborate [bis(triethylammonium) decaboranate(10)], [(C2H5)3NH]2[B10H10], was determined and refined (space group Pmmn, no. 59, a = 989.7, b = 1333.7, c = 903.7 pm). The compound is a versatile starting material for many substances containing the [BioHio]2- entity and its derivatives. The closo-[B10H10]2- cluster is a bicapped square antiprism which is only slightly distorted. Its deviation from D4d symmetry is smaller than that of the B10 cages in every other compound containing this entity that have been structurally characterised. The presence of additional (N )H ---B3 interactions in form of multiple-centre bonds between the cations and the anions, which were postulated earlier and which should influence the cage symmetry, could not be confirmed. At 55 °C, the transition into a high temperature phase was investigated by X-ray powder diffraction. The high temperature phase crystallises in the tetragonal crystal system (a = 946.9, c = 1351.0 pm).