The lithiation of N,N’-bis(trimethylsilyl)ethylenediamine, 1, by 2 equiv of methyllithium in diethyl ether yields the dimeric diethyl ether adduct [{Li[N(SiMe(3))CH(2)CH(2)NSiMe(3)]Li . OEt(2)}(2)], 2. Recrystallization of 2 from benzene gives quantitatively the unsolvated trimer [{Li[N(SiMe(3))CH(2)CH(2)NSiMe(3)]Li}(3)], 3. The solution dynamics of 2 and 3 in toluene have been investigated using variable temperature multinuclear NMR spectroscopy. In solution, 2 is undergoing a rapid exchange process involving an equilibrium between unsolvated and diethyl ether solvated dimers, whereas compound 3 exists in a temperature dependent equilibrium of dimeric and trimeric species, of which the trimer is fluxional and exchanges inequivalent ligands by an intramolecular distortion of the Li6N6 cage structure. Crystals of 2 are monoclinic, of space group P2(1)/n (No. 14), with a = 10.692(9) Angstrom, b = 16.192(2) Angstrom, c = 24.04(4) Angstrom, beta = 101.16(5)degrees, V = 4083(8) Angstrom(3), and Z = 4. Crystals of 3 are trigonal, of space group R(3) over barm$ (No. 166), a = 17.765(1) Angstrom, c = 13.394(1) Angstrom, V = 3660.5(5) Angstrom(3), Z = 3.