Monomeric di-t-butylmethyleneaminoboranes

Abstract

The following new di-t-butylmethyleneaminoboranes have been prepared (the reagents in parentheses): Bu^t₂C:NBPh₂(from Ph₂BCl + Bu^t₂C:NLi); Bu^t₂C:NBCl₂(BCl₃+ Bu^t₂C:NLi); and Bu^t₂C:NBBuⁿ₂(Bu^t₂C:NBCl₂+ 2BuⁿLi or Buⁿ₂BCl + Bu^t₂C:NLi). These di-t-butylmethyleneaminoboranes are monomeric in benzene solution, with i.r. azomethine stretching frequencies in the range 1812–1839 cm^–1. Their ¹¹B n.m.r. show resonances at 32 ± 4 p.p.m. relative to BF₃,OEt₂ as is consistent with boron being in a three-co-ordinate environment. Their ¹H n.m.r. spectra have only a singlet absorption attributable to the t-butyl protons, even at –60°, interpreted as indicating that they probably contain linear CN[graphic omitted]B groups. Features of their mass spectra, which confirm their monomeric state in the gas phase, are briefly discussed.