A solid state and theoretical study of the solvent effects controlling the mono- and di-lithiation of aromatic primary amines

Reaction of 1-naphthylamine, 4-tritylaniline or 4-methylaniline with two equivalents of (BuLi)-Li-n in Et2O or thf affords rare geminal N,N-dilithiates of general formula (L)(n).((LiNAr)-N-2)(10) (L = Et2O, n = 6, Ar = 1-C10H7 1, C6H4-4-CPh3 2; L = thf, n = 10, Ar = C6H4-4-Me 3). X-Ray crystal structure analyses reveal that the core (Li14N10)(6-) frameworks consist of two fused rhombic dodecahedra. Ab initio M. O. calculations on the mono- and di-lithiation of 1-naphthylamine and 4-methylaniline suggest that the selectivity with which polymetallation occurs is solvent dependent and so help to rationalise the experimentally observed structures.