Bermuda-clusters…? On the interaction of chelating bipyridines with subvalent Ga⁺ and In⁺ salts of the [Al(OR^F)₄]⁻ WCA

GRAPHICAL ABSTRACT

ABSTRACT

Facile access to univalent Ga⁺ and In⁺ salts of the perfluorinated [Al(OR^F)₄]⁻ anion (R^F = C(CF₃)₃) allowed, for the first time, an investigation of the coordination chemistry of these simple cations. After investigating phosphanes, ethers, N-heterocyclic carbenes as well as bulky 2,6-^tBu₂-pyridine or pyrazine as ligands, the application of the classical 2,2'-bipyridine (bipy) ligand gave very unexpected results: bipy triggers a disproportionation of the univalent gallium salt [Ga(C₆H₅F)₂]⁺[Al(OR^F)₄]⁻. In the resultant monomeric and paramagnetic [Ga(bipy)₃]²⁺ complex, the gallium cation is coordinated in a distorted octahedral fashion by three bipy ligands. Electron paramagnetic resonance showed the ligand to be non-innocent, and the radical is the ligand centered with a Ga^III cation. By contrast, upon changing to [In(C₆H₅F)₂]⁺[Al(OR^F)₄]⁻, highly charged triangular and rhombic In₃- and In₄-clusters are formed, i.e. [In₃(bipy)₆]³⁺, [In₃(bipy)₅]³⁺, and [In₃(bipy)₆]⁴⁺. These clusters are formed by an unusual cationic cluster formation mechanism that is induced by the high lattice energies of the resulting AB₃ and AB₄ salts as well as charge transfer from bipy ligand to In⁺ cation.

KEYWORDS:

• Gallium
• indium
• cluster
• subvalent
• bipyridine
• non-innocent ligand
• EPR

Funding

This work was supported by the DFG.

Notes

1. Available at www.iolitec.de.