Abstract
Schnöckel's [(AlCp*)(4) ] and Jutzi's [SiCp*][B(C(6) F(5) )(4) ] (Cp*=C(5) Me(5) ) are landmarks in modern main-group chemistry with diverse applications in synthesis and catalysis. Despite the isoelectronic relationship between the AlCp* and the [SiCp*](+) fragments, their mutual reactivity is hitherto unknown. Here, we report on their reaction giving the complex salts [Cp*Si(AlCp*)(3) ][WCA] ([WCA](-) =[Al(OR(F) )(4) ](-) and [F{Al(OR(F) )(3) }(2) ](-) ; R(F) =C(CF(3) )(3) ). The tetrahedral [SiAl(3) ](+) core not only represents a rare example of a low-valent silicon-doped aluminium-cluster, but also-due to its facile accessibility and high stability-provides a convenient preparative entry towards low-valent Si-Al clusters in general. For example, an elusive binuclear [Si(2) (AlCp*)(5) ](2+) with extremely short Al-Si bonds and a high negative partial charge at the Si atoms was structurally characterised and its bonding situation analysed by DFT. Crystals of the isostructural [Ge(2) (AlCp*)(5) ](2+) dication were also obtained and represent the first mixed Al-Ge cluster.