Reinvestigation of Reactions of HgPh with Eu and Yb Metal and the Synthesis of a Europium(II) Bis(tetraphenylborate).

Europium bis(tetraphenylborate) [Eu(thf)][BPh]⋅thf containing a fully solvated [Eu(thf)] cation, was synthesized by protolysis of "EuPh" (from Eu and HgPh) with EtNHBPh, and the structure was determined by single-crystal X-ray diffraction. Efforts to characterize the putative "PhLn" (Ln = Eu, Yb) reagents led to the synthesis of a mixed-valence complex, [(thf)Yb(-Ph)Yb(Ph)(thf)]⋅2thf, resulting from the reaction of Yb metal with HgPh at a low temperature. This mixed-valence Yb/Yb compound was studied by Yb-NMR spectroscopy and single-crystal X-ray diffraction, and the oxidation states of the Yb atoms were assigned.