TY - JOUR
T1 - Experimental and theoretical studies of the vibrational and electronic spectra of a lanthanide ion at a Site of T
h symmetry
T2 - Pr
3+ in Cs
2NaPr(NO
2)
6
AU - Li, Wenyu
AU - Ning, Lixin
AU - Faucher, Michèle D.
AU - Tanner, Peter A.
PY - 2011/9/19
Y1 - 2011/9/19
N2 - The Pr
3+ ion in Cs
2NaPr(NO
2)
6 is situated at a site of T
h symmetry with 12-coordination to O atoms of bidentate nitrito groups. First-principles calculations of the vibrational modes of the complex were carried out using the density functional theory with the generalized gradient approximation Perdew-Burke-Ernzerhof exchange-correlation functional. The calculations that treated the Pr
3+ 4f electrons as valence electrons showed better agreement with the experimental vibrational assignments compared with those treating the 4f electrons a part of the inner core. The
1D
2 →
3H
4 emission spectra of Cs
2NaPr(NO
2)
6 at 7 K enabled assignments to be made for the crystal-field (CF) levels of the ground-state multiplet. The emission of the dilute system Cs
2NaY(NO
2)
6:Pr
3+ was dominated by NO
2
- triplet emission, which was quenched at elevated temperatures by energy transfer to trace Eu
3+ impurity. From magnetic dipole calculations and the vibronic fingerprint, detailed assignments are given for the complex 10 K electronic absorption spectrum of Cs
2NaPr(NO
2)
6 between 3940 and 18800 cm
-1, and the derived Pr
3+ 4f
2 energy-level data set has been fitted by calculation. By comparison with Cs
2NaPrCl
6, the fourth-order CF parameter in Cs
2NaPr(NO
2)
6 is relatively small so that interaction with a 4fnp configuration is not important. From the NO
2
- absorption bands above 20 000 cm
-1, the N-O bond length change upon excitation is small, whereas the angle O-N-O opens by more than 10° in the triplet state. By contrast to the NO
2
- internal vibration frequencies, which except for the wagging mode show only minor changes with the environment, the triplet-state energy shows a linear decrease with an increase of the lanthanide (Ln
3+) ionic radius in Cs
2NaLn(NO
2)
6. Using the eigenvectors from the energy-level fit, the variation of the inverse magnetic susceptibility with temperature has been calculated between 1 and 100 K and the values are somewhat lower than those from experiment. © 2011 American Chemical Society.
AB - The Pr
3+ ion in Cs
2NaPr(NO
2)
6 is situated at a site of T
h symmetry with 12-coordination to O atoms of bidentate nitrito groups. First-principles calculations of the vibrational modes of the complex were carried out using the density functional theory with the generalized gradient approximation Perdew-Burke-Ernzerhof exchange-correlation functional. The calculations that treated the Pr
3+ 4f electrons as valence electrons showed better agreement with the experimental vibrational assignments compared with those treating the 4f electrons a part of the inner core. The
1D
2 →
3H
4 emission spectra of Cs
2NaPr(NO
2)
6 at 7 K enabled assignments to be made for the crystal-field (CF) levels of the ground-state multiplet. The emission of the dilute system Cs
2NaY(NO
2)
6:Pr
3+ was dominated by NO
2
- triplet emission, which was quenched at elevated temperatures by energy transfer to trace Eu
3+ impurity. From magnetic dipole calculations and the vibronic fingerprint, detailed assignments are given for the complex 10 K electronic absorption spectrum of Cs
2NaPr(NO
2)
6 between 3940 and 18800 cm
-1, and the derived Pr
3+ 4f
2 energy-level data set has been fitted by calculation. By comparison with Cs
2NaPrCl
6, the fourth-order CF parameter in Cs
2NaPr(NO
2)
6 is relatively small so that interaction with a 4fnp configuration is not important. From the NO
2
- absorption bands above 20 000 cm
-1, the N-O bond length change upon excitation is small, whereas the angle O-N-O opens by more than 10° in the triplet state. By contrast to the NO
2
- internal vibration frequencies, which except for the wagging mode show only minor changes with the environment, the triplet-state energy shows a linear decrease with an increase of the lanthanide (Ln
3+) ionic radius in Cs
2NaLn(NO
2)
6. Using the eigenvectors from the energy-level fit, the variation of the inverse magnetic susceptibility with temperature has been calculated between 1 and 100 K and the values are somewhat lower than those from experiment. © 2011 American Chemical Society.
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U2 - 10.1021/ic201225k
DO - 10.1021/ic201225k
M3 - RGC 21 - Publication in refereed journal
SN - 0020-1669
VL - 50
SP - 9004
EP - 9013
JO - Inorganic Chemistry
JF - Inorganic Chemistry
IS - 18
ER -