Synthesis and crystal structure of the two lithium hypersilylcuprates LiCu2[Si(SiMe3)(3)](3) and [Li-7((OBu)-Bu-t)(6)][Cu-2{Si(SiMe3)(3)}(3)]

The two hypersilylcuprates LiCu(2)Hyp(3) (2) and [Li-7((OBu)-Bu-t)(6)][Cu(2 )Hyp(3)] (3) (Hyp = Si(SiMe3)(3)) were synthesized by reactions of unsolvat ed lithium hypersilanide, Li-Hyp with hypersilylcopper and (CuOBu)-Bu-t, re spectively. Both contain the novel A-frame trihypersilyldicuprate anion [Cu 2- Hyp(3)](-). In the former case a molecular compound is produced containi ng intimate ion pairs. In the latter case the cuprate anion and the unique large [Li-7((OBu)-Bu-t)(6)](+) cation form a salt-like compound, only spari ngly soluble in unpolar solvents. According to NBO analyses the bonding wit hin the trihypersilyldicuprate moiety is best described by interaction of a bridging lewis-basic hypersilanide anion with two lewis-acidic hypersilyl copper fragments.