From mixed group 13 cations [M(AlCp*)3]+ (M = Ga/In/Tl) to an Al4+ cluster† † Electronic supplementary information (ESI) available. CCDC 2193060, 2193049, 2194540, 2194543, 2193851, 2194404 and 2194403. For ESI and crystallographic data in CIF or other electronic format see https://doi.org/10.1039/d2sc04637g

ABSTRACT: AlCp*-complexes with transition metals have shown to be highly reactive and enable C–H or Si–H bond activation. Yet, complexes of AlCp* with low-valent main-group metals are scarce. Here, we report the syntheses of [M(AlCp*)3][Al(ORF)4] (RF = C(CF3)3) with M = Ga, In, Tl, which include the first covalent Al–In and Al–Tl bonds. For M = Ga, AlCp*-coordination induced the formation of the dication [Ga2(AlCp*)6]2+ in the solid state, which exhibits a solvent and temperature dependent monomer–dimer equilibrium in solution. By contrast, the In and Tl complexes are monomeric and prone to reduction to the metal by the electron-rich AlCp*-moieties. The QTAIM analysis suggests that the metal centres are already highly reduced in the complexes, while the positive charge is distributed onto the AlCp* units. Addition of Me3TACN (1,4,7-trimethyl-1,4,7-triazacyclononane) to the Ga- and Tl-complex salts resulted in an isomerization to the novel low-valent Al4+ cation [(Me3TACN)Al(AlCp*)3][Al(ORF)4]. Intermittently formed tetrahedral GaAl3+ clusters could be structurally characterized. From a detailed mechanistic study of this isomerization, the very high yield and clean preparation of [(Me3TACN)Al(AlCp*)3][Al(ORF)4] was devised from [M(Me3TACN)][Al(ORF)4] (M = Ga, Tl) and [(AlCp*)4]. Mixed low-valent group 13 cations with formally reduced metal atoms have been prepared via addition of [(AlCp*)4] to the low-valent cation salts of Ga, In and Tl. Addition of an aza-crown ether resulted in isomerization to a novel Al4+ cluster.

SUBMITTER: Krossing I 

PROVIDER: S-EPMC9600313 | biostudies-literature | 2022 Sep

REPOSITORIES: biostudies-literature