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 or HC5Me4SiMe3 in THF or hexane at room temperature resulted in the formation of metallocene complexes [(eta(5):eta(1)-C(5)Me4SiMe(2)CH(2))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 eta(5)-form and to the other in a mu-eta(5):eta(1)-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)(2)LnH(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 H-2. The reaction of the yttrium hydride complex 2a with 1 equiv of p-methoxyphenylisocyanide yielded the ethylene diamido complex [(C5Me4SiMe3)(2)YN(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)(2)Ln(mu-H)(3)Ir(C5Me5)] (Ln = Y (4a), Dy (4b), Lu (4c)) with release of H-2.