Synthesis and Characterization of Imidocubanes with Exocube GeIV and SnIV Substituents:  [M(μ3-NGeMe3)]4 (M = Sn, Ge, Pb); [Sn(μ3-NSnMe3)]4

The heteroleptic lithium amide, [(Me3Sn)(Me3Ge)NLi·(Et2O)]2 (2), reacts with MCl2 (M = Sn, Ge, Pb) to yield the corresponding cubane complexes [M(μ3-NGeMe3)]4 [M = Sn (3), Ge (4), Pb (5)]. In an analogous reaction with SnCl2, the lithium stannylamide, [(Me3Sn)2NLi·(Et2O)]2 (1), produces the mixed-valent Sn congener [Sn(μ3-NSnMe3)]4 (6). All imidocubanes contain both di- and tetravalent group 14 metals that are bridged by N. These structures are comprised of M4N4 (M = Sn, Pb, Ge) cores that possess varying distortion from perfect cube geometry. The Pb derivative (5) exhibits enhanced volatility and vapor-phase integrity.