Cationic cluster formation versus disproportionation of low-valent indium and gallium complexes of 2,2’-bipyridine

Abstract

Group 13 MI compounds often disproportionate into M0 and MIII. Here, however, we show that the reaction of the MI salt of the weakly coordinating alkoxyaluminate [GaI(C6H5F)2]+[Al(ORF)4]− (RF=C(CF3)3) with 2,2'-bipyridine (bipy) yields the paramagnetic and distorted octahedral [Ga(bipy)3]2+•{[Al(ORF)4]−}2 complex salt. While the latter appears to be a GaII compound, both, EPR and DFT investigations assign a ligand-centred [GaIII{(bipy)3}•]2+ radical dication. Surprisingly, the application of the heavier homologue [InI(C6H5F)2]+[Al(ORF)4]− leads to aggregation and formation of the homonuclear cationic triangular and rhombic [In3(bipy)6]3+, [In3(bipy)5]3+ and [In4(bipy)6]4+ metal atom clusters. Typically, such clusters are formed under strongly reductive conditions. Analysing the unexpected redox-neutral cationic cluster formation, DFT studies suggest a stepwise formation of the clusters, possibly via their triplet state and further investigations attribute the overall driving force of the reactions to the strong In−In bonds and the high lattice enthalpies of the resultant ligand stabilized [M3]3+{[Al(ORF)4]−}3 and [M4]4+{[Al(ORF)4]−}4 salts.

Taming the Cationic Beast: Novel Developments in the Synthesis and Application of Weakly Coordinating Anions

“…[363] Furthermore,inthe case of the [In(C 6 H 5 F) 2 ] + cation, the large and weakly coordinating [Al(OR F ) 4 ] À ion gives rise to such alarge reduction in lattice enthalpy that cationic cluster formation can be induced upon the addition of the bidentate N-donor bipyridine ligand. [364] [364] …”

“…The iridium(III) cationic species [Ir(P t Bu 2 Ph) 2 (H) 2 ][B(Ar CF3 ) 4 ], supported by two agostic interactions from the t Bu groups on the phosphine ligands,i sr eadily formed by abstraction of an Xl igand from Ir(P t Bu 2 Ph) 2 (H) 2 X( where X = F, Cl, or OTf) by Na[B(Ar CF3 ) 4 ]. [364] Scheme 16. [364] Scheme 16.…”

Tris(1‐methyl‐imidazol‐2‐yl)phosphane Complexes of Pnictogen, Tetrel, and Triel Cations

“…Reactions of P(Im) 3 with indium(I)triflate in a variety of solvents gave a mixture of products. The cleanest reaction was observed in trifluoromethylbenzene, in which a grey precipitate was formed after stirring at room temperature for two days . Extraction of the grey precipitate with MeCN gave a phosphorus‐containing compound ( 31 P δ =−125.9 ppm) with the same chemical shift as that isolated from a reaction of two equivalents of P(Im) 3 and In(OTf) 3 in MeCN, and identified as [{P(Im) 3 } 2 In][OTf] 3 .…”

Synthesis, Structure, and Properties of Al(Rbpy)3 Complexes (R = t-Bu, Me): Homoleptic Main-Group Tris-bipyridyl Compounds

“…7 More recently, the [Ga(bpy) 3 ] 2+ complex was isolated and characterized. 8 Both complexes contain Ga 3+ metal ions, where the latter complex contains two neutral bpy ligands and one radical bpy anion as discussed below. Group 3 [Sc(bpy) 3 ] 0 and group 14 [Si(bpy) 3 ] n (where n = 4+ to 1+) have been described but not structurally characterized.…”