Lanthanide Terminal Hydride Complexes Bearing Two Sterically Demanding C₅Me₄SiMe₃ Ligands. Synthesis, Structure, and Reactivity

The acid−base reaction between lanthanide tris(alkyl) complexes Ln(CH2SiMe3)3(THF)2 and 2 equiv of HC5Me4SiMe3 in THF or hexane at room temperature resulted in the formation of metallocene complexes [(η5:η1-C5Me4SiMe2CH2)Ln(C5Me4SiMe3)(THF)] (Ln = Y (1a), Nd (1b), Sm (1c), Dy (1d), Lu (1e)), in which the metal center is bonded to one C5Me4SiMe3 ligand in a normal η5-form and to the other in a μ-η5:η1-chelate fashion through metalation of a methyl group of the SiMe3 substituent. Hydrogenolysis of 1a−e in toluene at room temperature afforded the corresponding metallocene terminal hydride complexes [(C5Me4SiMe3)2LnH(THF)] (Ln = Y (2a), Nd (2b), Sm (2c), Dy (2d), Lu (2e)). Complexes 2a,d,e were isolated and structurally characterized by X-ray analysis, whereas 2b,c, which possess larger metal ions, existed only in solution in the presence of H2. The reaction of the yttrium hydride complex 2a with 1 equiv of p-methoxyphenylisocyanide yielded the ethylene diamido complex [(C5Me4SiMe3)2YN(Ar)(CH)]2 (Ar = C6H4-OMe-p (3)). The reaction of 2a, 2d, and 2e with a late transition metal hydride complex (C5Me5)IrH4 gave the corresponding Ln/Ir heterobimetallic trihydride complexes [(C5Me4SiMe3)2Ln(μ-H)3Ir(C5Me5)] (Ln = Y (4a), Dy (4b), Lu (4c)) with release of H2.