Ytterbium compounds

Figure 5.8. Lanthanide Ln203 oxides (cubic cI80-Mn2O3 type, on the left side) and Pb alloys (LnPb3, cubic cP4-type, on the right). The trends of the lattice parameter and of the heat of formation are shown (see the text and notice the characteristic behaviour of Eu and Yb). A schematic representation of the energy difference between the divalent and trivalent states of an ytterbium compound is shown. Apromff represents the promotion energy from di- to trivalent Yb metal, A,//11, and Ar/Ynl are the formation enthalpies of a compound in the two cases in which there is no valence change on passing from the metal to the compound the same valence state (II or III) is maintained.

FIGURE 16 SEM and TEM image of spherical particles composed of ytterbium compound nanotubes. Reprinted with permission from Yada et al. (2004). Copyright 2004 Wiley-VCH. 

The only ytterbium compound of commercial interest is ytterbium oxide (Yb203). This compound is used to make alloys and special types of ceramics and glass. In 2007, ytterbium oxide sold for about 450 per kilogram. 

In the ytterbium case, a 60 40 mixture of two Yb(ll) isomers could be isolated in 68% yield. The isomers differ from one another by the alignment of the Buc substituents on both Cp rings of the Pf ligands. In the major isomer of the Yb complex the Buc substituents on both Cp rings of the /Pf ligands are eclipsed. In neither isomer is there a metal interaction Yb-Yb (4.94, 5.00 A). In the samarium case, only the anti,anti-compound similar to the // ,tf // -ytterbium compound was obtained (Scheme 42). In the samarium complex there is also no Sm-Sm metal interaction (4.93 A).216... 

X-ray diffraction studies on yttrium and ytterbium" compounds (C5H5)2MR2A1R2 have established their structures as of type 58 with the characteristically acute M-C-Al bond angle at the hypercarbon atom that shows involvement in a 3c-2e bond to the metal atoms while bonding normally, by three 2c-2e bonds, to the methyl hydrogen atoms. 

For all preparations of the dysprosium and ytterbium compounds as well as the compounds of M = Ga, Pb, second phases appear in the samples, showing that the compounds R3MC,. have an x value less than unity. From observations of the changes in lattice parameters with composition in the compound Nd3lnC, the limiting... 

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