Synthesis and Characterisation of Novel Bis(diphenylphosphane oxide)methanidoytterbium(III) Complexes.

Reaction of [YbCp(2)(dme)] (Cp = cyclopentadienyl, dme = 1,2 dimethoxyethane) with bis(diphenylphosphano)methane dioxide (H(2)dppmO(2)) leads to deprotonation of the ligand H(2)dppmO(2) and oxidation of ytterbium, forming an extremely air-sensitive product, [Yb(III)(HdppmO(2))(3)] (1), a six-coordinate complex with three chelating (OPCHPO) HdppmO(2) ligands. Complex 1 was also obtained by a redox transmetallation/protolysis synthesis from metallic ytterbium, Hg(C(6)F(5))(2,) and H(2)dppmO(2). In a further preparation, the reaction of [Yb(C(6)F(5))(2)] with H(2)dppmO(2), not only yielded compound 1, but also gave a remarkable tetranuclear cage, [Yb(4)(µ-HdppmO(2))(6)(µ-F)(6)] (2) containing two [Yb(µ-F)](2) rhombic units linked by two fluoride ligands and the tetranuclear unit is encapsulated by six bridging HdppmO(2) donors. The fluoride ligands of the cage result from C-F activation of pentafluorobenzene and concomitant formation of p-H(2)C(6)F(4) and m-H(2)C(6)F(4), the last being an unexpected product.