Tetra-, Penta-, and Hexanuclear Yttrium Hydride Clusters from Half-Sandwich Bis(anninobenzyl) Complexes Containing Various Cyclopentadienyl Ligands

The novel series of half-sandwich tetrahydrofuran (THF)-free yttrium bis(arninobenzyl) complexes [(C(5)Me(4)R)-Y(CH(2)C(6)H(4)NMe(2-o))(2)] (R = SiMe(3) (1a), Me (1b), Et (1c), H (1d)) was prepared by treatment of [Y(CH(2)C(6)H(4)NMe(2-o))(3)] with C(5)Me(4)RH, and their reactions with H(2) and with PhSiH(3) in aromatic solvents or in THF were examined. The reaction of la with H(2) in benzene gave the pentanudear yttrium decahydride complex [{Cp'Y(mu-H)(2)}(5)] (Cp' = eta(5)-C(5)Me(4)SiMe(3)) (3), which could not be obtained by the reaction of the corresponding THF-coordinated dialkyl complex [Cp'Y(CH(2)SiMe(3))(2)(THF)] with H(2). The reaction of 1b with H(2) in toluene gave the partially hydrogenated tetranudear mixed aminobenzyl/hydride complex [(Cp*Y)(2)(CH(2)C(6)H(4)NMe(2-o))(mu-H)(3)](2) (4; Cp* = eta(5)-C(5)Me(5)), and no further hydrogenation reaction occurred, whereas the corresponding reaction of 1b with H(2) in THF gave the pentanuclear yttrium polyhydride complex [{Cp*Y(mu-H)(2)}(5) (THF)(2)] (5). Hydrogenolysis of the sterically less demanding C(5)Me(4)H-ligated complex 1d with H(2) in THF gave the tetranuclear octahydride complex [{Cp(H)Y(mu-H)(2)}(4)(THF)(4)] (6; Cp(H) = eta(5)-C(5)Me(4)H), which has one coordinating THF ligand on each metal atom. The hexanuclear yttrium dodecahydride complex {[Cp*Y(mu-H)(2)](6)} (7) was obtained by treatment of 1b with PhSiH(3) in benzene. The structures of 1a,b,d, 3, 4, {{(C(5)Me(4)Et)Y(mu-H)(2)}(5)(THF)(2)] (5'), 6, and 7 were determined by X-ray single-crystal diffraction studies.