Synthesen und Eigenschaften von Piperidin-N-oxyboranen / Synthesis and Properties of Piperidine-N-oxyboranes

Piperidine-N-oxyboranes and 2,2,6,6-Tetramethylpiperidine-N-oxyboranes have been prepared starting from halogenoboranes by three methods: a) By reaction with N-hydroxypiperidine and triethylamine; b) by cleavage of the Si -O-bond in piperidine-N-oxy-trimethylsilanes and c) by reaction with metallated piperidine-N-oxy compounds. Diboryloxides and diborylamides, resp., are obtained upon reaction of piperidine-N-oxybrom oboranes with hexamethyldisiloxane and hexamethyldisilazane. Steric influences upon reactivity and spectroscopic properties are discussed. The compounds are characterized by elemental analysis, mass and NMR spectroscopy ( 1 H , 11 B , 13 C, 14 N, 29 Si). An X-ray analysis has been carried out for tris(2,2,6,6-tetram ethylpiperidine-1-oxy)borane 13.