Organolanthanides-XVI. Preparation and structure of bis(η⁵-cyclopentadienyl)bis(triphenylphosphine oxide)ytterbium(II)-the first X-ray crystal structure of a phosphine oxideorganolanthanide(II) complex

Reaction of Cp₂Yb(DME) (Cp = cyclopentadienyl; DME = 1,2-dimethoxyethane) with triphenylphosphine oxide yields Cp₂Yb(OPPh₃)₂. The X-ray crystal structure shows eight-coordinate ytterbium with a pseudo-tetrahedral arrangement of two oxygen donor atoms and the centroids of two eclipsed η₅-cyclopentadienyl rings. Surprisingly short Yb-O distances (2.30(2); 2.33(2) Å) and the absence of major inter-ligand contacts indicate an uncrowded arrangement.