Dicyclopentadienyl ytterbium

Tricyclopentadienyl ytterbium reacts with liquid ammonia with formation of a stable 1 1 complex, which can be sublimed, but which decomposes above 200°C with formation of dicyclopentadienyl ytterbium amide and cyclopentadiene (E.O. Fischer and H. Fischer, 1966). The corresponding 1 1 adducts of NH3 could also be isolated for (C5Hj)3Pr and (C5H5)3Sm (Birmingham and Wilkinson, 1956), as well... 

Dimeric dicyclopentadienyl ytterbium chloride monomerizes at the ion source temperature of 250°C, but at 180°C removal of cyclopentadienyl ligands is found with formation of YbjCl J ions (Muller, 1969). 

Dicyclopentadienyl erbium methyl and dicyclopentadienyl ytterbium methyl react with alkynes like HC CC(CH3)3 with formation of dimeric alkynide-bridged complexes of the type [Cp2RC=CC(CH3)3]2 (Atwood et al., 1981). 

Tricyclopentadienyl ytterbium and tricyclopentadienyl neodymium react with various terminal alkynes by liberating cyclopentadiene although CjHg is a stronger protic acid. While the formation of dimeric dicyclopentadienyl ytterbium derivatives... 

Investigations by Bielang and R.D. Fischer (1978) demonstrate that the reactions of dicyclopentadienyl ytterbium chloride with lithium di(cyclohexyI)phosphide, lithium cyclohexylphosphide and lithium phenylphosphide are rather complicated. The decomposition behavior of these very sensitive substances is complex. It was possible to isolate Cp2YbP(QHji)2, but Cp2YbPHPh and Cp2YbPHQH decompose with formation of polymeric species [CpYbPPh] and [CpYbPQH,] . 

The first compounds containing bonds between dicyclopentadienyl rare earth moieties and elements of group IV have been prepared by Schumann and Cygon (1978). Dicyclopentadienyl erbium chloride and dicyclopentadienyl ytterbium chloride react with lithium triphenylgermane or triphenylstannane with formation of dicyclopentadienyl erbium triphenylgermane and -stannane and dicyclopentadienyl ytterbium triphenylstannane, the latter containing two tetrahydrofuran molecules coordinated to ytterbium ... 

Dicyclopentadienyl ytterbium is also available by other methods (Calderazzo et al., 1966), and the Sm, Eu and Yb derivatives result from the interaction of dicyclopentadienyl mercury with the activated lanthanides in tetrahydrofuran (Suleimanov et al., 1982b) ... 

Several dicyclopentadienyl ytterbium hydrocarbyls were prepared by reaction of Cp2Yb(DME) with HgR2 (R = C6Fs, CgClj, C=CPh) (Deacon and Wilkinson 1988). 

Ytterbium dicyclopendienide was prepared by reducing dicyclopentadienyl ytterbium chloride with finely dispersed sodium metal in tetrahydrofurane (Calderazzo et al., 1966). Samarium(II) dicyclopentadienide was isolated as the 1-tetra-hydrofuranate. This compound was prepared by reaction between SmfCsHj), and potassium naphthalene in tetrahydrofurane (Watt et al., 1969). It is insoluble in this solvent and very air-sensitive. Desolvation of the compound at elevated temperature under reduced pressure is accompanied by decomposition. 

Structural studies by Baker, Brown, and Raymond (42) have shown the dimeric nature of lanthanide dicyclopentadienyl halides. They reported that the molecular structure of [Y (C H CH ) Cl] consists of two ytterbium atoms, each with two n -bound methyl-cyclopentadienyl rings, which are nearly symmetrically bridged by the two chlorine atoms. The crystal structure of Yb(C(.H Me was reported by Halton et al. (43). The complex actually nas a dimeric structure, Cp2YbMe2YbCp2, remarkably similar to Me2ALMe2 AlMe2 The overall molecular geometry is identical with that or the chloride analogue Yb(C H CH )2CI. 

Iodine cleaves one erbium-cyclopentadienyl bond in tricyclopentadienyl erbium with formation of pink dicyclopentadienyl erbium iodide (Maginn et al., 1963), and the tricyclopentadienyl complexes of neodymium and ytterbium are cleaved by hydrogen cyanide with formation of the corresponding dicyclopentadienyl lanthanide cyanide (Kanellakopulos et al., 1974). The colors and some physical data of the cyclopentadienyl rare earth halides and cyanides are given in table 4. 

The first described organometallic compound of a rare earth element in the oxidation state + 2 was dicyclopentadienyl europium, prepared by E.O. Fischer and H. Fischer (1964) by reacting europium with cyclopentadiene in liquid ammonia. Ytterbium metal reacts in the same way (E.O. Fischer and H. Fischer, 1965b). By... 

The tetrahydrofuran complex of dicyclopentadienyl samarium is made by reduction of tricyclopentadienyl samarium with KCjgHg in naphthalene in the presence of tetrahydrofuran and was isolated as a purple pyrophoric product (Watt and Gillow, 1969). Ytterbium also reacts with thallous cyclopentadienide in dimethoxyethane in the presence of a little metallic mercury with formation of Cp2Yb DME (Deacon et al., 1982a). 

A metal vapor technique provides a very interesting route to the preparation of Sm(II) or Yb(II) organometallic species. Thus W.J. Evans et al. (1980, 1981a, 1982) were able to prepare several substituted dicyclopentadienyl samarium and ytterbium complexes. Sm(C5Mes)2 was the first known soluble divalent organosamarium complex. 

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