Synthesis and Characterization of Silyldichloramines, Their Reactions with F- Ions, Stability of N2CI2 and NCI2(-), and Formation of NCI3 (Postprint)

摘要

Only two silyldichloramines, (C6H5)3SiNCl2 and (CH3)3SiNCl2, have been reported in the literature. The synthesis of the former was successfully repeated, and its structure was established by single crystal X-ray diffraction and vibrational spectroscopy. Attempts to prepare (CH3)3SiNCl2 were unsuccessful, however, a new trialkylsilyldichloramine, t-BuMe2Si-NCl2, was prepared and characterized by Raman and multinuclear NMR spectroscopy. The reaction of t-BuMe2SiNCl2 with (CH3)4NF in CHF3 solution at -78 deg C, followed by removal of all volatile products at -30 deg C, produced the expected t- BuMe2SiF by-product and a white solid consisting of NCl3 absorbed on Me4NCl. The NCl3 could be reversibly desorbed from the substrate and was identified as a neat liquid at room temperature by Raman spectroscopy. The observed final reaction products are consistent with the formation of an unstable N(CH3)4+NCl2(-) intermediate which decomposes to N(CH3)4+Cl(-) and NCl molecules which can dimerize to N2Cl2. Theoretical calculations confirm that NCl2(-) can readily lose Cl(-) and that N2Cl2 also possesses a low barrier towards loss of N2 to give chlorine atoms and, thus, can account for the formation of NCl3.