Low-Valent Ge2 and Ge4 Species Trapped by N-Heterocyclic Gallylene

摘要

Much progress has been made in the field of low-valent main group 13-15 compounds. The disilicon molecule LSi=SiL (L = :C(N(2,6-iPr2C6H3)CH}2) and the closely related species E2L2 (i.e. "Ge2", "P2", "As2") were major discoveries in recent years. Even the dicarbon congeners C2L2 should be accessible, as was deduced from quantum chemical studies. N-heterocyclic carbenes (NHCs) turned out to be the key for opening the door to this new chemistry, and their heavier main group 13-14 analogs such as gallylenes (NHGa), silylenes (NHSi), germylenes (NHGe), expand this library of "multitalented" Lewis base ligands for stabilizing reactive species and unusual bonding situations. In particular the NHGa compound Ga(DDP) (DDP = HC(CMeNC6H3-2,6-iPr2)2) behaves as a potent trapping ligand and a selective reducing agent as well. This unique combination of properties has been used for the synthesis of the metalloid tin clusters Sn7L'2, Sn_(17)L and the bismuthenes Bi2L'2 (L' = (DDP)XGa; X = Cl, CF3SO3).