DIVALENT LANTHANIDE CHEMISTRY; BIS (PENTAMETHYLCYCLOPENTADIENYL) EUROPIUM(II) AND YTTERBIUM(II) DERIVATIVES [electronic resource] : CRYSTAL STRUCTURE OF BIS(PENTAMETHYLCYCLOPENTADIENYL) YTTERBIUM (II)TETRAHYDROFURAN HEMI (TOLUENE) AT 176K.
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| Format: | Government Document Electronic eBook |
| Language: | English |
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Berkeley, Calif. : Oak Ridge, Tenn. :
Lawrence Berkeley National Laboratory ; distributed by the Office of Scientific and Technical Information, U.S. Dept. of Energy,
1980.
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| Abstract: | Red, paramagnetic (μ{sub B} = 7.99 B.M., 5-50K) bis(pentamethylcyclopentadienyl) europium (II)(tetrahydrofuran)(diethylether), (Me₅C₅)₂Eu(THF)(Et₂O) is isolated from reaction of three molar equivalents of sodium pentamethylcyclopentadienide and europium trichloride in refluxing tetrahydrofuran, after crystallization from diethyl ether. The monotetrahydrofuran complex, (Me₅C₅)₂Eu(THF), may be isolated by use of toluene rather than diethyl ether as the crystallization solvent. Red, diamagnetic bis(pentamethylcyclopentadienyl)ytterbium(II)(tetrahydrofuran) is isolated from the reaction of ytterbium dichloride and sodium pentamethylcyclopentadienide in refluxing tetrahydrofuran. The diethyl ether complex, (Me₅C₅)₂Yb(OEt₂), may be isolated by crystallization of the tetrahydrofuran complex from diethylether, The hemi-toluene complex, (Me₅C₅)₂ Yb(THF) · 1/2 toluene, can be isolated by recrystallization of the tetrahydrofuran complex from toluene. As these divalent metallocenes are the first hydrocarbon-soluble lanthanide derivatives to be isolated we have examined the latter complex by X-ray crystallography. Crystals of (Me₅C₅)₂Yb(OC₄H₈) · 1/2(C₆H₅cH₃) crystalline in the monoclinic system, P2₁/n, with a = 11.358(8) Å, b = 21.756(19) Å, c = 10.691(7) Å, and β = 101.84(5){sup o} at 176K. For Z = 4 the calculated density is 1.37 g cm⁻³. The ytterbium atom is coordinated to the oxygen atom of a tetrahydrofuran molecule and to two pentamethyl cyclopentadienyl rings. The molecule has approximate c₂ symmetry about the Yb-0 bond. The Yb-0 distance is 2.41 Å, the Yb-C distances average 2.66 Å, and the Yb-Cp (centroid) distances average 2.37 Å. The Me₅C₅ rings are in a staggered configuration with respect to each other. The methyl groups of the Me₅C₅ groups are displaced by .03 to .21 Å from the planes of the five-membered rings away from the ytterbium atom. The toluene molecule is not coordinated to the complex and is on a center of symmetry in a disordered configuration. The 3466 data with F² > 3σ refined by full matrix least-squares to a conventional R factor of 0.036. |
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| Item Description: | Published through the Information Bridge: DOE Scientific and Technical Information. 04/01/1980. "lbl-10490" Inorganic Chemistry 19 10 ISSN 0020-1669; INOCAJ FT. Andersen, Richard A.; Templeton, David H.; Tilley, T.Don; Spencer, Brock; Ruben, Helena; Zalkin, Allan. Materials Sciences Division. |
| Physical Description: | 44 p. : digital, PDF file. |