Synthesis, and structural characterization of solvent-free divalent ytterbium bis(boratabenzene) and (cyclopentadienyl)(boratabenzene) complexes

The preparation and characterization of the solvent-free divalent ytterbium bis(boratabenzene) complex [C5H5BCH2(CH3)2P→BC5H5]2Yb (2a) and heteroleptic complexes [C5H3R1R2][C5H5BCH2(CH3)2P→BC5H5]Yb (3: R1 = SiMe3, R2 = H; 4: R1 = R2 = SiMe3) are reported. The interactions between the pendant neutral borabenzene and the ytterbium center were observed both in the solid-state and in benzene. Addition of external σ-donor solvent THF to the complexes caused a dissociation of the neutral borabenzene from the ytterbium center.