Organolanthanoids, 24 -: Organoamido- and aryloxo-lanthanoids, 21 -: Syntheses and structures of bis(aryloxo)fluoroytterbium(III) complexes, [Yb(OAr)2F(THF)]2 (OAr = OC6H2-2,6-tBu2-4-R;: R = H, Me, tBu), and bis(cyclopentadienyl)fluoroytterbium(III) complexes, [YbCp2F]3, [Yb(MeCp)2F]4, [YbCp2F(OPPh3)]2, and [Yb(MeCp)2F(THF)]2

Reaction of [Yb(OAr)(2)(THF)(3)] (OAr = OC6H2-2,6-tBu(2)-4-R; R = H, Me, tBu) with perfluorodecalin in THF at room temperature results in C-F activation and formation of the first heteroleptic aryloxofluorolanthanoid complexes, [Yb-(OAr)(2)F(THF)](2). Oxidation of his (cyclopentadienyl)ytterbium(II) with perfluoro(methylcyclohexane) or perfluorodecalin in DME surprisingly gives unsolvated [YbCp2F](3). The analogous reaction of bis(methylcyclopentadienyl)ytterbium(II) yields unsolvated [Yb(MeCp)(2)F](4), whilst in THF the oxidation provides [Yb(MeCp)(2)F(THF)](2). Treatment of [YbCp2F(THF)](2) with triphenylphosphane oxide gives [YbCp2F(OPPh3)](2). X-ray structure determinations revealed [Yb(OAr)(2)F(THF)](2) (R = H or tBu) to be centrosymmetric fluoride-bridged dimers with five-coordination for ytterbium. Examination of the structures of the cyclopentadienyl complexes showed that [YbCp2F](3) is trimeric with formal eight-coordination for ytterbium and a planar (YbF)(3) ring, whereas [Yb(MeCp)(2)F](4) is an eight-coordinate tetramer having a puckered (YbF)(4) ring with F-Yb-F angles of ca. 90 degrees and Yb-F-Yb angles close to 180 degrees [178.9(4), 168.4(3)degrees]. Both [Yb(-MeCp)(2)F(THF)](2) and [YbCp2F(OPPh3)](2) are nine-coordinate fluoride-bridged dimers.