Dipotassium bis([8]annulene)ytterbate(II) and -calcate(II)

Article abstract of DOI:10.1021/om00120a010

The title compounds were prepared by stoichiometric reaction of cyclooctatetraene, potassium, and either ytterbium or calcium, in liquid ammonia solution. The dimethoxyethane adducts of K₂[Yb(C₈H₈)₂] and K₂[Ca(C₈H₈)₂] are crystalline and have similar X-ray powder patterns; K₂[Yb(C₈H₈)₂] and K₂[Ca(C₈H₈)₂] have identical infrared spectra. X-ray structure analysis of [K(C₄H₁₀O₂)]₂[Yb(C₈H ₈)₂] shows planar parallel eclipsed [8]annulene rings sandwiching a centrosymmetric ytterbium. A potassium coordinated with dimethoxyethane is at the opposite side of each ring. Crystals of [K(C₄H₁₀O₄)]₂[Yb(C₈H ₈)₂] crystallize in the triclinic system of space group P1 with a = 9.346 (4) ?, b = 9.775 (4) ?, c = 7.740 (4) ?, α = 91.72 (4)°, β = 109.16 (4)°, and γ = 86.22 (4)° at T = 23°C.