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Improved point‐charge model within the INDO/S‐CI method for describing the ligand excited states of lanthanide coordination compounds
Author(s) -
Batista Hélcio J.,
Longo Ricardo L.
Publication year - 2001
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.10031
Subject(s) - chemistry , lanthanide , excited state , zindo , ion , charge (physics) , atomic orbital , atomic physics , ab initio , point particle , linear combination of atomic orbitals , computational chemistry , density functional theory , electron , physics , molecule , quantum mechanics , organic chemistry , basis set
Due to the spatial extent of the 5 s and 5 p filled orbitals of lanthanide ions, the shielding of the nuclear charge is not perfect at close distances to the ion. Thus, ligand atoms should experience different effective charge depending upon their distance to the central ion. Using electrostatic arguments and ab initio calculations for Eu 3+ , we have proposed an improved model that describes the ion as an effective charge, q ( r ), whose value has the following radial dependence, q ( r )=3+14 e − Ar 2. This functional form of the point charge has been implemented into the ZINDO program and INDO/S‐CI calculations have been performed for the Eu(btfa) 3 bipy, Eu(btfa) 3 ⋅2H 2 O, Eu(bzac) 3 bipy, and Eu(bzac) 3 ⋅2H 2 O compounds. The comparison with the experimental absorption spectrum was used to optimize the exponent A parameter. Application of this model to several other Eu 3+ coordination compounds yielded better results for the calculated absorption spectra than the fixed 3+ point‐charge model. © 2001 John Wiley & Sons, Inc. Int J Quantum Chem, 2001