1,2,4-Tri(tBu)cyclopentadienyl gallium (Cp′′′Ga) as a versatile reagent for the synthesis of Lewis adducts and ionic compounds

Abstract

The reaction of (η⁵-1,2,4-tri(^tBu)cyclopentadienyl)gallium (Cp′′′Ga; 1) with boron(III) species resulted in a diversity of complexes with different oxidation states and coordination modes, respectively. The reaction of 1 with triarylborane B(C₆F₅)₃ readily forms η⁵-Cp′′′Ga → B(C₆F₅)₃ (2) adducts, where gallium exhibits a +I oxidation state. However, using the bulky substituted borane halide (TipBBr₂) leads to the formation of an ionic compound, [η⁵-Cp′′′B-Tip]⁺[GaBr₄]⁻ (3). Furthermore, the reaction of 1 with BI₃ experiences unforeseen insertion of the boron atom between the Cp′′′ ring and Ga that produces η⁵-Cp′′′B → GaI₃ adduct (4). All new compounds were fully characterized by multinuclear NMR, elemental analysis, and X-ray diffraction.