Synthesis and Structural Characterization of Novel Ytterbium(III) Complexes with both a μ‐Oxo Group and Bridged Indenyl Ligands, and Ytterbium(II) Complexes with Bridged Indenyl Ligands

Abstract

The reactivity of the ytterbium(III) amide [(Me3Si)2N]3Yb(μ‐Cl)Li(thf)3 with different bridged indene compounds in the presence of external donor ligands was studied. Reaction of [(Me3Si)2N]3Yb(μ‐Cl)Li(thf)3 with the corresponding 1,2‐bis(indenyl)ethane [(CH2)2(C9H7)2] or Me2Si(C9H7)2, followed by the addition of excess thf, produced a novel tetranuclear ytterbium complex [{η5:η5‐(CH2)2(C9H6)2}Yb(μ‐Cl)(μ3‐O)Yb(Cl)N(SiMe3)2Li(thf)4]2 (1) or a novel dinuclear ytterbium complex [η5:η5‐(CH3)2Si(C9H6)2Yb]2(μ‐Cl)(μ‐O)Li(thf)2 (2), respectively. Treatment of [(Me3Si)2N]3Yb(μ‐Cl)Li(thf)3 with (CH2)2(C9H6SiMe3)2 (3) or Me2Si(C9H7)2 under different conditions produced ytterbium(II) complexes [η5:η5‐(CH2)2(C9H5SiMe3)2]Yb(thf)2·(C6H14)0.5 (4) and [η5:η5‐(CH2)2(C9H5SiMe3)2]Yb·dme (5) or [η5:η5‐(CH3)2Si(C9H6)2]Yb·tmeda (6), respectively. Interaction of the ytterbium(III) amide [η5:η5‐(CH2)2(C9H6)2]YbN(SiMe3)2 with excess tmeda afforded the ytterbium(II) complex [η5:η5‐(CH2)2(C9H6)2]Yb·tmeda (7). All the compounds were fully characterized by spectroscopic methods and elemental analyses. Complexes 1, 2, and 4 were additionally characterized by single‐crystal X‐ray diffraction analyses. The solvents and temperature effects on the reaction are discussed. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)

Synthesis, Characterization, and Structures of Divalent Europium and Ytterbium N,N-Dimethylaminodiboranates

“…53,54 The Yb-H distances range from 2. 35(3) to 2.54(3) Å and are consistent with those previously observed. [52][53][54] The Eu(DME) complex 3 is monomeric; both DMADB ligands and both DME molecules chelate to the metal center ( Figure 5).…”

“…51 All of the BH 3 groups are bound to the Yb center by means of two hydrogen bridges; as expected, the κ 2 H Yb-B distances in 2 are much longer than those observed for κ 3 H tetrahydroborate groups bound to Yb II , which range from 2.596(5) to 2.692(4) A ˚.53,54 The Yb-H distances range from 2. 35(3) to 2.54(3) A ˚and are consistent with those previously observed. [52][53][54] The Eu(DME) complex 3 is monomeric; both DMADB ligands and both DME molecules chelate to the metal center (Figure 5).…”

“…26 The reactions of Ln[N(SiMe 3 ) 2 ] 3 (μ-Cl)Li(THF) 3 , where Ln = Eu or Yb, with indenes or fluorenes bearing pendant amine or ether functional groups, yield the corresponding lanthanide(II) metallocenes. [27][28][29][30][31][32][33][34][35][36][37] Similarly, treatment of the substituted benzyl complex Sm(CH 2 C 6 H 4 -2-NMe 2 ) 3 with the bulky cyclopentadiene C 5 (C 6 H 4 -4-n-Bu) 5 H (Cp BIG H) at 60 °C yields the Sm II product Sm(Cp BIG ) 2 . 38 A closely related phenomenon is sterically induced reduction, [9][10][11]39,40 which is characteristic of tris(pentamethylcyclopentadienyl) complexes Ln(C 5 Me 5 ) 3 .…”

“…For example, reactions of europium(III) halides with bulky cyclopentadienide anions or of europium(III) metallocene halides with alkyllithium reagents can afford organometallic compounds of Eu II . − The Yb III complex [(C 5 H 4 Me) 2 YbMe] 2 slowly reduces to the corresponding (C 5 H 4 Me) 2 Yb complex upon being heated to 80 °C or photolyzed in toluene . The reactions of Ln[N(SiMe 3 ) 2 ] 3 (μ-Cl)Li(THF) 3 , where Ln = Eu or Yb, with indenes or fluorenes bearing pendant amine or ether functional groups, yield the corresponding lanthanide(II) metallocenes. − Similarly, treatment of the substituted benzyl complex Sm(CH 2 C 6 H 4 -2-NMe 2 ) 3 with the bulky cyclopentadiene C 5 (C 6 H 4 -4- n -Bu) 5 H (Cp BIG H) at 60 °C yields the Sm II product Sm(Cp BIG ) 2 …”

Rare earth metal benzyl complexes bearing bridged-indenyl ligand for highly active polymerization of methyl methacrylate

“…However, the reported anionic rare earth metal complexes showed poor ability to control polymer molecular weights. On the other hand, while a large spectrum of rare earth metal complexes with different electronic and steric configurations have been well documented, the bridged-indenyl-ligated rare earth metal complexes are relatively limited [16][17][18][19][20][21][22][23][24][25][26][27]. Herein, we would like to report the novel anionic bridged-indenyl rare earth metal benzyl complexes, as well as their extremely high activity for the polymerization of methyl methacrylate with molecular weights controllable under certain conditions.…”