The recent synthesis of the Ln3+ complexes, (C5H4SiMe3)3Ln, 1, and the Ln2+ complexes, [K(2.2.2-cryptand)][(C5H4SiMe3)3Ln], 2, for all the lanthanide elements except radioactive promethium, has allowed the first comparison of all the lanthanide elements in the same coordination environment in both +2 and +3 oxidation states. It was expected that the complexes of the traditional six Ln2+ ions, i.e., Eu2+, Yb2+, Sm2+, Tm2+, Dy2+, and Nd2+, would have physical properties consistent with reduction of a 4fn Ln3+ complex, 1, to a 4fn+1 Ln2+ complex, 2, and would differ from the complexes of La2+, Ce2+, Pr2+, Gd2+, Tb2+, Ho2+, Er2+, and Lu2+ that have 4fn5d1 ground states in the coordination environment of 2. However, structural, spectroscopic, and density functional theory analysis indicate that only four of the traditional six Ln2+ ions have properties consistent with 4fn+1 configurations. The Nd2+ and Dy2+ ions appear to be 4fn5d1 species in 2. In light of these results, the physical properties of other complexes of Nd2+ and Dy2+ previously reported in the literature will be evaluated and the implications of these results in f element chemistry will be discussed.

Physical properties of rare-earth complexes in the +2 oxidation state

249th National Meeting (2015)

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