Ytterbium under high pressure

Indoles react with epoxides and aziridines in the presence of Lewis acids (see 20.4.1 for reaction of indolyl anions with such reactants) with opening of the three-membered ring and consequent 3-(2-hydroxyethylation) and 3-(2-aminoethylation) of the heterocycle. Both ytterbium triflate and phenylboronic acid are good catalysts for reaction with epoxides under high pressure silica gel is also an effective catalyst, but reactions are slow at normal pressure and temperature. Reaction with aziridines can be catalysed by zinc triflate or boron trifluoride. °... 

The electrical resistivity of the intermediate-valent ytterbium compound YbAu2ln has been investigated under high-pressure conditions (Alami-Yadri et al., 1998) up to 8 GPa. The Kondo temperature decreases with increasing pressure, while the residual electrical resistiv-... 

Fee ytterbium at atmospheric pressure and room temperature is a metal. With the application of pressure Yb becomes a semi-metal and then a semiconductor. The semiconducting fee phase transforms into a metallic bcc phase at about 40 kbar (Jayaraman 1978), while Divakar et al. (1984) give 33 kbar. The relative volume change is about 3%. Another structural phase transformation (bcc-hcp) occurs at 260-309 kbar (cf. Takemura and Syassen 1985). Similar to europium the p-V isotherm of the adjacent trivalent reference element lutetium is found to intersect that of Yb at about 200 kbar (at 300 K). Syassen et al. (1981,1982) measured the L, absorption in Yb under high pressure up to 340 kbar with a conventional laboratory spectrometer. Divalent Yb clearly transforms into a mixed valent state at 40 kbar... 

The ring opening of epoxides with amines was investigated under several conditions including high pressure and catalysis by ytterbium triflate (Scheme 10.14) [43]. It was found that the combination of pressme and Yb(OTf)3 catalysis was... 

The existence of the ytterbium sesquicarbide with the cubic Pu2C3-type structure was not established (Spedding et al. 1958) under common conditions. However, this type of ytterbium carbide can be prepared at high pressures, like the other high-pressure heavy-lanthanide sesquicarbides (Krupka and Krikorian 1970). 

Kaminska A, Kozanecki A, Trushkin S, Suehoeki A (2010) Spectroscopy of ytterbium-doped InP under high hydrostatic pressure. Phys Rev B 81 165209... 

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