in hexane byproducts: LiF; dropping a soln. of LiN(SiMe3)2 in n-hexane to a soln. of 2,4,6-tri-t-butylphenyl-fluoro-(methylamino)borane in n-hexane under N2 at -50°C and allowing to stand overnight; removal of the solvent under reduced pressure and subliming the iminoborane from the residue in an oil pump vacuum, elem. anal.;