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Derivation of Lanthanide Series Crystal Field Parameters From First Principles
Authors:Dr. Julie Jung  M. Ashraful Islam  Dr. Vincent L. Pecoraro  Dr. Talal Mallah  Dr. Claude Berthon  Dr. Hélène Bolvin
Affiliation:1. Theoretical division, Los Alamos National Laboratory, Los Alamos, New Mexico, 87545 USA;2. Laboratoire de Chimie et Physique Quantiques, CNRS, Université Toulouse III, 118 route de Narbonne, 31062 Toulouse, France;3. Department of Chemistry, Willard H. Dow Laboratories, University of Michigan, Ann Arbor, Michigan, 48109 USA;4. Institut de Chimie Moléculaire et des Matériaux d'Orsay, CNRS, Université de Paris-Sud 11, 91405 Orsay Cedex, France;5. CEA, Nuclear Energy Division, Radiochemistry Processes Department, DRCP, BP 17171, 30207 Bagnols sur Cèze, France
Abstract:Two series of lanthanide complexes have been chosen to analyze trends in the magnetic properties and crystal field parameters (CFPs) along the two series: The highly symmetric LnZn16(picHA)16 series (Ln=Tb, Dy, Ho, Er, Yb; picHA=picolinohydroxamic acid) and the [Ln(dpa)3](C3H5N2)3 ⋅ 3H2O series (Ln=Ce–Yb; dpa=2,6-dipicolinic acid) with approximate three-fold symmetry. The first series presents a compressed coordination sphere of eight oxygen atoms whereas in the second series, the coordination sphere consists of an elongated coordination sphere formed of six oxygen atoms. The CFPs have been deduced from ab initio calculations using two methods: The AILFT (ab initio ligand field theory) method, in which the parameters are determined at the orbital level, and the ITO (irreducible tensor operator) decomposition, in which the problems are treated at the many-electron level. It has been found that the CFPs are transferable from one derivative to another, within a given series, as a first approximation. The sign of the second-order parameter urn:x-wiley:09476539:media:chem201903141:chem201903141-math-0001 differs in the two series, reflecting the different environments. It has been found that the use of the strength parameter S allows for an easy comparison between complexes. Furthermore, in both series, the parameters have been found to decrease in magnitude along the series, and this decrease is attributed to covalent effects.
Keywords:ab initio calculations  crystal field theory  lanthanides  magnetic properties
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