TY - JOUR
T1 - Structural, spectroscopic, and theoretical comparison of traditional vs recently discovered Ln2+ ions in the [K(2.2.2-cryptand)][(C5H4SiMe3)3Ln] complexes
T2 - The variable nature of Dy2+ and Nd2+
AU - Fieser, Megan E.
AU - Macdonald, Matthew R.
AU - Krull, Brandon T.
AU - Bates, Jefferson E.
AU - Ziller, Joseph W.
AU - Furche, Filipp
AU - Evans, William J.
N1 - Publisher Copyright:
© 2014 American Chemical Society.
PY - 2015/1/14
Y1 - 2015/1/14
N2 - The Ln3+ and Ln2+ complexes, Cp′3Ln, 1, (Cp′ = C5H4SiMe3) and [K(2.2.2-cryptand)][Cp′3Ln], 2, respectively, have been synthesized for the six lanthanides traditionally known in +2 oxidation states, i.e., Ln = Eu, Yb, Sm, Tm, Dy, and Nd, to allow direct structural and spectroscopic comparison with the recently discovered Ln2+ ions of Ln = Pr, Gd, Tb, Ho, Y, Er, and Lu in 2. 2-La and 2-Ce were also prepared to allow the first comparison of all the lanthanides in the same coordination environment in both +2 and +3 oxidation states. 2-La and 2-Ce show the same unusual structural feature of the recently discovered +2 complexes, that the Ln-(Cp′ ring centroid) distances are only about 0.03 Å longer than in the +3 analogs, 1. The Eu, Yb, Sm, Tm, Dy, and Nd complexes were expected to show much larger differences, but this was observed for only four of these traditional six lanthanides. 2-Dy and 2-Nd are like the new nine ions in this tris(cyclopentadienyl) coordination geometry. A DFT-based model explains the results and shows that a 4fn5d1 electron configuration is appropriate not only for the nine recently discovered Ln2+ ions in 2 but also for Dy2+ and Nd2+, which traditionally have 4fn+1 electron configurations like Eu2+, Yb2+, Sm2+, and Tm2+. These results indicate that the ground state of a lanthanide ion in a molecule can be changed by the ligand set, a previously unknown option with these metals due to the limited radial extension of the 4f orbitals.
AB - The Ln3+ and Ln2+ complexes, Cp′3Ln, 1, (Cp′ = C5H4SiMe3) and [K(2.2.2-cryptand)][Cp′3Ln], 2, respectively, have been synthesized for the six lanthanides traditionally known in +2 oxidation states, i.e., Ln = Eu, Yb, Sm, Tm, Dy, and Nd, to allow direct structural and spectroscopic comparison with the recently discovered Ln2+ ions of Ln = Pr, Gd, Tb, Ho, Y, Er, and Lu in 2. 2-La and 2-Ce were also prepared to allow the first comparison of all the lanthanides in the same coordination environment in both +2 and +3 oxidation states. 2-La and 2-Ce show the same unusual structural feature of the recently discovered +2 complexes, that the Ln-(Cp′ ring centroid) distances are only about 0.03 Å longer than in the +3 analogs, 1. The Eu, Yb, Sm, Tm, Dy, and Nd complexes were expected to show much larger differences, but this was observed for only four of these traditional six lanthanides. 2-Dy and 2-Nd are like the new nine ions in this tris(cyclopentadienyl) coordination geometry. A DFT-based model explains the results and shows that a 4fn5d1 electron configuration is appropriate not only for the nine recently discovered Ln2+ ions in 2 but also for Dy2+ and Nd2+, which traditionally have 4fn+1 electron configurations like Eu2+, Yb2+, Sm2+, and Tm2+. These results indicate that the ground state of a lanthanide ion in a molecule can be changed by the ligand set, a previously unknown option with these metals due to the limited radial extension of the 4f orbitals.
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U2 - 10.1021/ja510831n
DO - 10.1021/ja510831n
M3 - Article
C2 - 25541886
AN - SCOPUS:84921059061
SN - 0002-7863
VL - 137
SP - 369
EP - 382
JO - Journal of the American Chemical Society
JF - Journal of the American Chemical Society
IS - 1
ER -