Trans influence in a mer-octahedral triiodidolanthanide: triiodidotris(tetrahydrofuran-κO)ytterbium(III)

The structure of the six-coordinate title complex, [YbI₃(C₄H₈O)₃], is the first mer-octahedral form of an LnI₃L₃ lanthanide (Ln) compound with neutral L ligands, and is closely related to that of several of the seven-coordinate LnX₃L₄ series of compounds, where X = Cl, Br or I and L = tetrahydrofuran (THF), isopropanol, pyridine or water. A structural trans effect can be assigned to YbI₃(THF)₃, in contrast to the LnX₃L₄ compounds, where steric and crystal packing effects are significant. The Yb—I bond lengths are 2.9543 (4) and 2.9151 (6) Å for I trans and cis to I, respectively, and the Yb—O bond lengths are 2.299 (5) and 2.251 (3) Å for O trans and cis to I, respectively. The crystal packing allows for six contact distances as weak C—H...I interactions in the range 3.10–3.24 Å. The title molecule has a crystallographic twofold axis passing through a THF O atom, the trans I atom and the Yb atom.