Mechanochemical C–H bond activation: Synthesis of the tuckover hydrides, (C5Me5)2Ln(μ-H)(μ-η1:η5-CH2C5Me4)Ln(C5Me5) from solvent-free reactions of (C5Me5)2Ln(μ-Ph)2BPh2 with KC5Me5

Attempts to synthesize the sterically crowded complexes (C5Me5)3Ln of the smallest lanthanide metals, Ln = Tm and Lu, from (C5Me5)2Ln(μ-Ph)2BPh2 and KC5Me5 via mechanochemical methods has revealed C–H bond activation chemistry: the tuckover hydride complexes, (C5Me5)2Ln(μ-H)(μ-η1:η5-CH2C5Me4)Ln(C5Me5), were observed in low crystalline yields. In the case of Ln = Yb, attempts to synthesize the cationic precursor, (C5Me5)2Yb(μ-Ph)2BPh2, from the reaction of (C5Me5)2Yb(η3-C3H5) and [HNEt3][BPh4] led to the reduction of the metal and the formation of the Yb(II) cationic complex, (C5Me5)Yb(μ-Ph)2BPh2.