This review addresses the coordination chemistry (mainly) enabled by using the univalent [M(fluoroarene) 2-3 ] + [Al(OR F ) 4 ] Àsalts (M=Ga, In; R F =C(CF 3 ) 3 ) as robust starting materials. In the course of this work, it became clear that the orbital energy of the ns 2 (n = 4, 5) lone pair in such [:M(L) n ] + cations reacts drastically depending on the quality of the ligand employed. Activation of the lone pair with strong σ-donor ligands might be used for bond activation and oxidative addition reactions. Yet, unexpectedly, using sterically undemanding and electron rich ligands with limited π-accepting properties, aggregation to highly charged and rather unusual univalent cluster cations [M n (L) m ]°+ (n = 2…5, m = 4…6, o = 3…5) was observed. An overview and rationalization of these findings is presented here.

The tetracationic, univalent cluster compounds [{M(dmpe)}4]4+ (M=Ga, In; dmpe=bis(dimethylphosphino)ethane) were synthesized as their pf salts ([pf]−=[Al(ORF)4]−; RF=C(CF3)3). The four‐membered ring in [{M(dmpe)}4]4+ is slightly puckered for M=Ga and almost square planar for M=In. Yet, although structurally similar, only the gallium cluster is prevalent in solution, while the indium cluster forms temperature dependent equilibria that include even the monomeric cation [In(dmpe)]+. This system is the first report of one and the same ligand inducing formation of isoelectronic and isostructural gallium/indium cluster cations. The system allows to study systematically analogies and differences with thermodynamic considerations and bonding analyses, but also to outline perspectives for bond activation using cationic, subvalent group 13 clusters.

Already 1 mol-% of subvalent [Ga(PhF)2]+[pf]– ([pf]– = [Al(ORF)4]– , RF = C(CF3)3) initiates the hydrosilylation of olefinic double bonds under mild conditions. Reactions with HSiMe3 and HSiEt3 as substrates...

Weakly coordinating anions (WCAs) are considered promising candidates for application as electrolytes in multivalent post‐lithium batteries. One strong candidate as electrolyte salt for Mg battery application is [Mg(L)x][Al(ORF)4]2 (L=MeCN (acetonitrile), DME (1,2‐dimethoxyethane); x=3, 6; RF=C(CF3)3) that contains [Al(ORF)4]− as one of the least coordinating WCAs known. Here we present a novel synthetic route, for which vibrational, NMR and XRD analyses show the formation of a clean, pristine electrolyte salt without the common contaminants found in published synthetic routes. The electrochemistry of this pristine and pure [Mg(DME)3][Al(ORF)4]2 electrolyte (0.2 m in DME) was investigated via cyclic voltammetry (CV). In contrast to previous publications using impure materials, the CV showed no sign for Mg deposition from the pristine electrolyte for all conditions tested. This also holds when including the additives LiCl, NaCl, MgCl2, Li[BH4] or a mixture of MgCl2/Mg[HMDS]2 (HMDS=hexamethyldisilazide) in THF. Quantum chemical calculations suggested the possibility of anion decomposition at the negative electrode, leading to an electronically insulating MgF2 layer (rutile structure) on all the electrode materials tested. This hypothesis was confirmed by an XPS investigation of electrodes exposed to the electrolytes containing the WCAs [Al(ORF)4]− and [Al(OC(H)(CF3)2)4]− at negative potentials, which only showed the presence of MgF2 for the [Al(ORF)4]− electrolyte, but not for the related [Al(OC(H)(CF3)2)4]− electrolyte (which allowed to deposit magnesium reversibly on the electrode).

Syntheses and characterization of two salts [(L)GaGa(L)][pf]2 ([pf]− = [Al(ORF)4]−; RF = C(CF3)3) are reported. They include the first dicationic digallene [(L)Ga⇆Ga(L)]2+ (L = CDPPh = C(PPh3)2) and a digallane...