SYNTHESIS AND STRUCTURE OF TRIPHENYLMETHYL DERIVATIVES OF YTTERBIUM [YB(THF)(6)](2+)[PH(3)C](2)(-) AND [(THF)(4)YB(MU-CL)(2)YB(THF)(4)](2+)[PH(3)CL](2)(-)

Ionic triphenylmethyl complexes of ytterbium [Yb(THF)(6)](2+)[Ph(3)C](-)(2) (1) and [(THF)(4)Yb(mu-Cl)(2)Yb(THF)(4)](2+)[Ph(3)C](-)(2) (2) have been synthesized by the reaction of Ph(3)CCl with ytterbium in THF. Complex 1 has also been prepared by the reaction of ytterbium with a dimer of triphenylmethyl radicals in THF. It was found that this reaction was catalyzed by ytterbium dihalides. According to X-ray diffraction result the crystal structures of 1 and 2 are composed of isolated ions. The [Yb(THF)(6)](2+) cation has an ideal octahedral coordination of the central Yb atom with the Yb-O distance of 2.390(7) Angstrom. The [(THF)(4)Yb(mu-Cl)(2)-Yb(THF)(4)](2+) cation is a centrosymmetrical dimer in which each Yb atom is bonded to four oxygen atoms of THF molecules and two (THF)(4)Yb units are linked via two symmetrical mu-Cl bridges, both Yb-Cl distances being 2.715(4) Angstrom. The [Ph(3)C](-) anion in 1 and 2 has a propeller-type geometry with the planar environment of the central carbon atom (within 0.02 Angstrom in 1 and 0.006. Angstrom in 2). The Ph rings are rotated out of the average CC3 plane of the central fragment of [Ph(3)C](-) anion by 28.2 degrees in 1 and by 26.6, 31.9, 33.7 degrees in 2.