Preparation, crystal structure, and spectroscopic characterization of [(H3C)(3)Si]NH(BCl2)

[(H3C)(3)Si]NH(BCl2) is formed during the reaction of boron trichloride wit h hexamethyldisilazane at low temperatures. The compound crystallizes monoc linic in space group P2(1)/c with a=953.8(2)pm, b=1059.9(1)pm, c = 867.4(1) pm, beta = 99.40(2)degrees; Z = 4. According to the single crystal X-ray d iffraction analysis (1275 symmetry independent reflections, R = 0.040), [(H 3C)(3)Si]NH(BCl2) exists as a dimer, in the crystal. The dimers have site s ymmetry C-i and, within the margins of error of the structure determination , point symmetry C-2h. A characteristic feature is a planar, almost square B-N-B-N four-membered ring with the trimethylsilyl groups in trans position . The compound has been characterised by MS-, H-1-, C-13-, B-11-, and Si-29 -NMR-spectroscopy.