Differentiating Chemically Similar Lewis Acid Sites in Heterobimetallic Complexes: The Rare-Earth Bridged Hydride (C5Me5)2Ln(μ-H)2Ln′(C5Me5)2 and Tuckover Hydride (C5Me5)2Ln(μ-H)(μ-η1:η5-CH2C5Me4)Ln′(C5Me5) Systems

Abstract

The challenge of differentiating the chemistry of two closely related Lewis acidic metals in heterobimetallic complexes was addressed by studying hydrogenolysis and C–H bond activation reactions of bimetallic rare-earth hydride complexes. Hydrogenolysis of equimolar amounts of Cp*2Lu(η3-C3H5) (1-Lu) and Cp*2Y(η3-C3H5) (1-Y) (Cp* = C5Me5) forms a mixture of hydride complexes, the heterobimetallic compound Cp*2Lu(H)2YCp*2 (2-Lu/Y) and the homobimetallic compounds (Cp*2LuH)2 (2-Lu/Lu) and (Cp*2YH)2 (2-Y/Y). This mixture can be analyzed and differentiated by 1H NMR spectroscopy due to the I = 1/2 89Y nucleus to reveal these three products in a ratio of approximately 86:10:4, respectively. Heating this mixture leads to C–H bond activation and formation of tuckover hydride complexes, the heterobimetallic compounds Cp*2Y(μ-H)(μ-η1:η5-CH2C5Me4)LuCp* (3-Y/Lu) and Cp*2Lu(μ-H)(μ-η1:η5-CH2C5Me4)YCp* (3-Lu/Y) and the homobimetallic compounds Cp*2Lu(μ-H)(μ-η1:η5-CH2C5Me4)LuCp* (3-Lu/Lu) and Cp*2Y(μ-H)(μ-η1:η5-CH2C5Me4)...