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

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)...