Ytterbium complexes pentamethylcyclopentadienyls

A similar reaction between diphenyl ditellurium and bis[pentamethylcyclopentadienyl] diamineytterbium in toluene produced the ytterbium complex with one benzenetellurolate, one amine ligand, and two cyclopentadienyl groups in a pseudotetrahedral arrangement ... 

Crystallographic data, bonding distances and angles in pentamethylcyclopentadienyl ytterbium complexes. 

By applying new vacuum line technology to liquid ammonia techniques, one can carry out clean high-yield syntheses of pentamethylcyclopentadienyl europium(II) and ytterbium(II) complexes from the respective metals (Wayda et al., 1984). The authors concluded that their reaction conditions produced genuinely stable metal-ammonia solutions, although the behavior of the two lanthanides differed in one particular aspect while there was no evidence for an isolable EU-NH3 bond, it was possible to prepare and characterize an unusual ytterbium complex coordinated to both a THF moiety and an ammonia molecule. 

Bis(pentamethylcyclopentadienyl) Complexes (MCp, of Calcium, Strontium, Barium, Samarium, Europium, and Ytterbium Bent ... 

Watson (1980), Watson et al. (1981) and TiUey and Andersen (1981b) prepared bis(pentamethylcyclopentadienyl) ytterbium, lutetium, neodymium and samarium chlorides and iodides. Some physical data of these compounds together with those of the other complexes with substituted cyclopentadienyl ligands are given in table 8. The following synthetic methods have been used ytterbium metal is oxidized by CjMejI in the presence of Lil in ether to give, via CjMejYbl, the complexes shown in eq. (20). In the absence of Lil, only dimeric pentamethylcyclopentadiene was isolated. 

Pentamethylcyclopentadienyl complexes of Sm(II), Eu(II) and Yb(II) have been prepared and characterized after 1980. Red bis(pentamethylcyclopentadienyl) europium(II) complexes with one coordinated THF or one THF and one Et20 are isolated from the reactions of europium trichloride and sodium pentamethylcyclo-pentadienide in refluxing tetrahydrofuran and crystallization from toluene or ether (Tilley et al., 1980). Red diamagnetic bis(pentamethylcyclopentadienyl)ytterbium(II) coordinated with THF or Et20 are formed in the analogous reaction, but using YbCl 2 as the starting material. 

When the THF complex is recrystalUzed from toluene, a hemitoluene complex (C5Me5)2Yb (THF)-(QH5CH3)i/2 precipitates, which X-ray structural determination (fig. 44, table 41) shows the ytterbium atom coordinated to two pentamethylcyclopentadienyl rings and the oxygen atom of the THF. The molecule has C2 symmetry about the Yb-O bond the pentamethylcyclopentadienyl rings are staggered with respect to each other. The toluene molecule is not coordinated to the ytterbium. It is on a center of symmetry in a disordered configuration. 

Watson s investigations of mixed alkyl/pentamethylcyclopentadienyl complexes of ytterbium and lutetium have shown that the polymerization occurs due to the successive insertion of olefine into the Ln-C bond. The process includes the p-hydride or p-alkyl decomposition of Ln-R intermediates. The splitting-off of the coordinative bonded ligand from REM precedes the above mentioned reactions (see Scheme XIII.l). 

Diethyl ether adducts of his(pentamethylcyclopentadienyl)europium(II) and -ytterbium(II). Excited-state energy transfer with organolanthanoid complexes, A. C. Thomas, A. B. Ellis, OrganometaUics 1985, 4, 2223. 

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