Low‐Valent MxAl3 Cluster Salts with Tetrahedral [SiAl3]+ and Trigonal‐Bipyramidal [M2Al3]2+ Cores (M=Si/Ge). Issue 8 (12th January 2023)

• Record Type: Journal Article
• Authors: Dabringhaus, Philipp; Zedlitz, Silja; Giarrana, Luisa; Scheschkewitz, David; Krossing, Ingo
• Is Part Of: Angewandte Chemie international edition. Volume 62:Issue 8(2023)
• Page Start: n/a
• Page End: n/a
• Publication Date: 2023-01-12
• Subjects: Aluminium -- Bond Theory -- Cluster Compounds -- Silicon -- Weakly-Coording Anions; Chemistry -- Periodicals; 540
• DOI: 10.1002/anie.202215170
• Languages: English
• ISSNs: 1433-7851

Abstract

Abstract: Schnöckel's [(AlCp*)4 ] and Jutzi's [SiCp*][B(C6 F5 )4 ] (Cp*=C5 Me5 ) 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(CF3 )3 ). The tetrahedral [SiAl3 ] + 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 [Si2 (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 [Ge2 (AlCp*)5 ] 2+ dication were also obtained and represent the first mixed Al−Ge cluster. Abstract : The elusive tetrahedral [Cp*Si(AlCp*)3 ] + cation is prepared as its aluminate salts starting from Jutzi's [SiCp*] + cation and Schnöckel's [(AlCp*)4 ]. Owing to its good accessibility, [SiAl3 ] + can act as starting point towards the synthesis of low‐valent silicon‐doped aluminium‐cluster cores as shown by the preparation of the larger [Si2 (AlCp*)5 ] 2+ cluster cation.