Synthesis and structures of the [benzamidinato]3- complexes Li3(tmeda)(L1)]2 and [Li(thf) 4][Li5(L2)(OEt2)2] [L1 = N(SiMe3)C(Ph)N(SiMe3) and L2 = N(SiMe3)C(C6H4-4)NPh]

Reduction at ambient temperature of each of the lithium benzamidinates [Li(L1)(tmeda)] or [{Li(L2)(OEt2) 2}2] with four equivalents of lithium metal in diethyl ether or thf furnished the brown crystalline [Li3(L 1)(tmeda)] (1) or [Li(thf)4][Li5(L 2)2(OEt2)2] (2), respectively. Their structures show that in each the [N(R1)C(R3)NR 2]3- moiety has the three negative charges largely localised on each of N, N' and R = Aryl); a consequence is that the "aromatic" 2,3- and 5,6-CC bonds of R3 approximate to being double bonds. Multinuclear NMR spectra in C6D6 and C 7D8 show that 1 and 2 exhibit dynamic behaviour. [The following abbreviations are used: L1 = N(SiMe3)C(Ph) N(SiMe3); L2 = N(SiMe3)C(C6H 4Me-4)N(Ph); tmeda = (Me2NCH2-)2; thf = tetrahydrofuran.] This reduction is further supported by a DFT analysis.