Crystal structure of the [(THF)Cs(μ-η5:η5-Cp′)3Yb]n oligomer

Abstract

The green compound poly[(tetrahydrofuran)tris[μ-η5:η5-1-(trimethylsilyl)cyclopentadienyl]caesium(I)ytterbium(II)], [CsYb(C8H13Si)3(C4H8O)]n or [(THF)Cs(μ-η5:η5-Cp′)3YbII]n was synthesized by reduction of a red THF solution of (C5H4SiMe3)3YbIII with excess Cs metal and identified by X-ray diffraction. The compound crystallizes as a two-dimensional array of hexagons with alternating CsI and YbII ions at the vertices and cyclopentadienyl groups bridging each edge. This, based off the six-electron cyclopentadienyl rings occupying three coordination positions, gives a formally nine-coordinate tris(cyclopentadienyl) coordination environment to Yb and the Cs is ten-coordinate due to the three cyclopentadienyl rings and a coordinated molecule of THF. The complex comprises layers of Cs3Yb3 hexagons with THF ligands and Me3Si groups in between the layers. The Yb—C metrical parameters are consistent with a 4f14 YbII electron configuration.

Keywords

• lanthanide
• caesium
• cyclopentadienide
• oligomer
• crystal structure