Synthesis, characterization and structures of diphenyldiaminosilanes bearing bulky substituents on nitrogen

Aminosilanes bearing bulky substituents on nitrogen centers, [(ArNH)2SiPh2] (Ar=2,6-iPr2C6H3 (1), 2,4,6-Me3C6H2 (2), 2,6-Et2C6H3 (3)), have been prepared in good yields by the addition of dichlorodiphenylsilane to the corresponding substituted monolithiated aniline. The new compounds have been characterized by elemental analysis and IR, EI mass and NMR (1H and 29Si) spectroscopic studies. The solid-state structures of 1 and 3 have been determined by single crystal X-ray diffraction studies. The molecules have a Cs symmetry and the two NH protons are approximately trans to each other. The amido nitrogen atoms show significant deviation from trigonal-planar geometry, as a result of which the observed SiN bonds are marginally longer than those observed in aminosilanes with planar nitrogen atoms.