Crystallographic studies of the boron–nitrogen bond in aminoboranes. Part 5. The crystal and molecular structure of 1,5,9-triaza-13-boratricyclotridecane

Abstract

Crystals of the title compound are orthorhombic, a= 8.69(1), b= 14.07(1), c= 8.48(1)Å, space group P2₁2₁2₁, and Z= 4. The atomic positions have been determined from diffractometer X-ray intensity data by the tangent refinement method and refined by full-matrix least-squares to R 0.050 for 414 reflections. The molecular symmetry is approximately C_3v(3m). The BN₃ system is almost planar but the carbon atoms lie out of this plane, by 0.3–0.4 Å above for atoms in the 3-, 7-, and 11-positions and by smaller amounts below for the remaining carbon atoms. Mean bond lengths are : B–N 1.431 (6), C–N 1.446(4), C–C 1.521 (5)Å and the B–N bond order obtained by molecular-orbital calculations is 1.4.