Low‐Valent M_<i>x</i>Al₃ Cluster Salts with Tetrahedral [SiAl₃]⁺ and Trigonal‐Bipyramidal [M₂Al₃]²⁺ Cores (M=Si/Ge)

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