Bent phenyl groups in lithiosilanes--crystal structures and interpretation of this unanticipated feature.

Based on the crystal structures of PMDTA coordinated lithiosilanes, the bend of aromatic substituents in anionic group fourteen and neutral group fifteen compounds (third row and higher) is explained by means of quantum chemical calculations, which indicate the deformation to be a result of Pauli-repulsion of the electrons in the occupied frontier orbitals.