Reinvestigation of Reactions of HgPh 2 with Eu and Yb Metal and the Synthesis of a Europium(II) Bis(tetraphenylborate).

Europium bis(tetraphenylborate) [Eu(thf) 7 ][BPh 4 ] 2 ⋅thf containing a fully solvated [Eu(thf) 7 ] 2+ cation, was synthesized by protolysis of "EuPh 2 " (from Eu and HgPh 2 ) with Et 3 NHBPh 4 , and the structure was determined by single-crystal X-ray diffraction. Efforts to characterize the putative "Ph 2 Ln" (Ln = Eu, Yb) reagents led to the synthesis of a mixed-valence complex, [(thf) 3 Yb II ( μ -Ph) 3 Yb III (Ph) 2 (thf)]⋅2thf, resulting from the reaction of Yb metal with HgPh 2 at a low temperature. This mixed-valence Yb II /Yb III compound was studied by 171 Yb-NMR spectroscopy and single-crystal X-ray diffraction, and the oxidation states of the Yb atoms were assigned.