SYNTHESIS OF BIS(TERT-BUTYLCYCLOPENTADIENYL)YTTERBIUM(II) - DERIVATIVES AND MOLECULAR-STRUCTURE OF BIS(TERT-BUTYLCYCLOPENTADIENYL)BIS(TETRAHYDROFURAN)YTTERBIUM(II)

Bis(η5-t-butylcyclopentadienyl)ytterbium(II) (t-C4H9C5H4)2Yb(THF)2 has been synthesized by metallic sodium reduction of the corresponding chloride (t-C4H9C5H4)2YbCl(THF) in THF. The reaction of (t-C4H9C5H4)2Yb(THF)2 with OPPh3 in toluene gives (t-C4H9C5H4)2Yb(OPPh3)(THF). (t-C4H9C5H4)2Yb(THF)2 crystallizes from THF in the monoclinic space group P21/n, with unit cell constants a 13.434(2), b 9.885(2), c 20.100(4) Å, β 105.34(1)°, V 2573.99 Å3 and Dcalcd 1.44 g cm-3 for Z = 4. Least-squares refinement of 4186 unique observed reflections led to a final R of 0.060. The two ring centroids of the t-butylcyclopentadienyl rings and the two oxygen atoms of the THF form a distorted tetrahedron around the central ion of ytterbium(II). The molecule has an approximate C2 cymmetry with the average bond distances: YbC(ring) 2.722(16) Å, YbO(THF) 2.431(8) Å, and YbCp (centroid) distance 2.442(0) Å. © 1990.