Synthesis and spectral characterization of diorganodiaminosilanes [(ArNH)2SiPhMe] (Ar = 2,6-iPr2C6H3; 2,4,6-Me3C6H2) and lithium silylamide [(2,6-Et2C6H3NLi)(2,6-Et2C6H3NH)SiPh2]

Aminosilanes bearing bulky substituents on nitrogen centers, [(ArNH)2SiPhMe] (Ar = 2,6-iPr2C6H3 (1), 2,4,6-Me3C6H2 (2)) and half-sandwich lithium silylamide [(2,6-Et2C6H3NLi)(2,6-Et2C6H3NH)SiPh2] (3) have been prepared and characterized by elemental analysis, IR, EI mass and NMR (1H and 29Si) spectroscopic studies. The solid state structures of 2 and 3 have been determined by single crystal X-ray diffraction studies. The molecule 2 has a C1 symmetry due to the steric crowding, and the two N–H protons are approximately trans to each other. The amido nitrogen atoms in 2 show significant deviation from trigonal-planar geometry, and as a result, the observed Si–N bonds are marginally longer than those observed in aminosilanes with planar nitrogen atoms. The molecule 3 exists as discrete dimer with an inversion center. The Li ion in 3 forms intramolecular π-complex with the neighboring aryl (2,6-Et2C6H3) group, to form a half-sandwich lithium silylamide.

A rare monolithium salt of a diorganodiaminosilane has been synthesized and structurally characterized; the lithium ion in this compound forms an unusual half-sandwich complex through the interaction of all six carbon atoms an adjacent aryl ring emanating from the –NHAr group on the central silicon.Figure optionsDownload as PowerPoint slide