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.