Electron density and bonding in B13C2

A single crystal of well-established composition B13C2 was used for a new and thorough structural analysis by X-ray diffraction. Unbiased atomic parameters refined from high-order data (R = 0.0256) were used for (X-X) difference Fourier syntheses representing dynamic deformation densities. Further studies of the electron density distributions were carried out by a multiple refinement using all reflections (R = 0.0278). The resulting atomic multipole coefficients were utilized for the evaluation of static electron deformation densities. The analysis of both experimental deformation density distributions corroborates the main features of the bonding in B13C2 deduced from earlier calculations on the isolated B12 icosahedron by Longuet-Higgins and Roberts using the linear combination of atomic orbitals. (Auth.)