Redox Non-Innocent Bis-Silylene Aluminium Complexes with a Carborane Backbone

Abstract

The redox non-innocent bis-silylenyl ortho-carborane ligands [Si^II(CC_cage)Si^II] (CC_cage = o-C₂B₁₀H₁₀, Si^II = ArC(N^tBu)₂Si; Ar = C₆H₅, p-^tBuC₆H₄), with their particular chelating and electronic properties, have been employed for the synthesis of new donor-stabilized Si^II→Al^III complexes that could act as precursors to low oxidation state aluminium complexes. Due to the redox non-innocence of the carborane backbone, aluminium(III) iodide complexes with three ligand oxidation states were characterized: neutral and radical anionic closo- as well as dianionic nido-C₂B₁₀ cores. Reduction at the aluminium center could also be enacted with potassium/napthalene leading to naphthalene derivatives {K[Si^II(CC_cage)Si^II]Al(C₁₀H₈)} from [1+4] cycloaddition reaction, pointing to transient low oxidation state aluminium species as likely intermediates.