Europium complexes pentamethylcyclopentadienyls

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

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. 

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. 

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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