Synthesis and Structure of (Hydridosilyl)hydrazines

A series of (hydridosilyl)hydrazines 1 – 12 has been prepared from the corresponding chloro‐or bromosilanes and hydrazines in the presence of triethylamine as an auxiliary base. Methylsilyl (MeH₂Si‐), dimethylsilyl (Me₂HSi‐), and phenylsilyl (PhH₂Si‐) groups have been introduced as substituents. NMR spectra (¹H, ¹³C, ¹⁵N, ²⁹Si) have been measured and used to determine the rotation barrier about the N — N bond in (PhH₂Si)(Me₂HSi)N — N(SiHMe₂) (9), which has been found to be 75 kJmol^–1. The crystal structure of (PhH₂Si)₂N — N(SiH₂Ph₂ (7) features each of the two NNSi₂ groups as nearly planar, but with a dihedral angle close to orthogonal. Such a structure is also implied for 9 on the basis of the NMR spectra.