Towards Naked Zinc(II) in the Condensed Phase: A Highly Lewis Acidic ZnII Dication Stabilized by Weakly Coordinating Carborate Anions

Abstract

AbstractThe employment of the hexyl‐substituted anion [HexCB11Cl11]− allowed the synthesis of a ZnII species, Zn[HexCB11Cl11]2, 3, in which the Zn2+ cation is only weakly coordinated to two carborate counterions and that is soluble in low polarity organic solvents such as bromobenzene. DOSY NMR studies show the facile displacement of at least one of the counterions, and this near nakedness of the cation results in high catalytic activity in the hydrosilylation of 1‐hexene and 1‐methyl‐1cyclohexene. Fluoride ion affinity (FIA) calculations reveal a solution Lewis acidity of 3 (FIA=262.1 kJ mol−1) that is higher than that of the landmark Lewis acid B(C6F5)3 (FIA=220.5 kJ mol−1). This high Lewis acidity leads to a high activity in catalytic CO2 and Ph2CO reduction by Et3SiH and hydrogenation of 1,1‐diphenylethylene using 1,4‐cyclohexadiene as the hydrogen source. Compound 3 was characterized by multinuclear NMR spectroscopy, mass spectrometry, single crystal X‐ray diffraction, and DFT studies.