A SAMARIUM ALKYL-ARYLOXIDE COMPLEX CONTAINING A TRIGONAL BIPYRAMIDAL CARBON-ATOM - X-RAY STRUCTURE OF [LI(THF)]2[SM(O-2,6-I-PR2C6H3)(3)(CH(2)SIME(3))(2)]

Reaction of Sm(O-2,6-i-Pr2C6H3)(3)(THF)(2) (1) with 3 equiv of LiCH(2)SiMe(3) in THF solution produces the salt complex (Me(3)SiCH(2))Sm[(mu-OAr)(mu-CH(2)SiMe(3))Li(THF)][(mu-OAr)(2)Li(THF)] (2, Ar = 2,6-i-Pr2C6H3) in 58% yield. H-1 and C-13 NMR are extremely complex, while Li-7 NMR is indicative of an equilibrium between 2 and free LiO-2,6-i-Pr2C6H3 in solution. Compound 2 contains a pentacoordinate samarium metal center ligated by one terminal and one bridging CH(2)SiMe(3) Ligand and three bridging O-2,6-i-Pr2CsH3 ligands. Each lithium atom is coordinated to one molecule of THF and either two aryloxide ligands or one aryloxide and one alkyl bridging Ligand. The bridging groups combine to make two fused four-membered metallacyclic rings, one Sm-O-Li-O and one Sm-C-Li-O ring [C-Sm = 2.564(10) Angstrom, C-Li = 2.219(20) Angstrom]. The molecule crystallizes in the monoclinic space group C2/c, with a = 32.017(8) A, b = 21.163(5) Angstrom, c = 22.354(6) Angstrom, beta = 128.03(1)degrees, V = 11931.34 Angstrom(3), d(calc) = 1.130 g cm(-3), and Z = 8.