Metallation of multifunctional secondary amines: the structural characterisation of the tripodal lithium amides {H3CC[CH2N(Li)R]3}3

Abstract

A series of trifunctional amines of the type H₃CC(CH₂NHR)₃[R = CH₃2, C₂H₅3, CH(CH₃)₂4, SiH(CH₃)₂5 or Si(CH₃)₃6] has been prepared and lithiated with n-butyllithium in hydrocarbon solvents. The tripodal lithium amides were found to be dimeric both in solution and in the solid state. Single-crystal X-ray structure analyses of {H₃CC[CH₂N(Li)CH(CH₃)₂]₃}₂9 and {H₃CC[CH₂N(Li)Si(CH₃)₃]₃}₂11 have established the central Li₆N₆ core in the molecular species. The geometrical requirements of the Li–N array cause a considerable distortion of the hydrocarbon skeleton which links the nitrogen centres.