title: Sparkle/PM6 Parameters for all Lanthanide Trications from La(III) to Lu(III).
abstract: PM6 is the first semiempirical method to be released already parametrized for the elements of the periodic table, from hydrogen to bismuth (Z = 83), with the exception of the lanthanides from cerium (Z = 58) to ytterbium (Z = 70). In order to fill this gap, we present in this article a generalization of our Sparkle Model for the quantum chemical semiempirical calculation of lanthanide complexes to PM6. Accordingly, we present Sparkle/PM6 parameters for all lanthanide trications from La(III) to Lu(III). The validation procedure again considered only high-quality crystallographic structures and included 633 complexes. Sparkle/PM6 unsigned mean errors UME(Ln-L)s, corresponding to all the interatomic distances between the lanthanide ion and the atoms directly coordinated to it, range from 0.066 to 0.086 Å for Gd(III) and Ce(III), respectively. These minimum and maximum UME(Ln-L)s across the lanthanide series are comparable to the Sparkle/AM1 values of 0.054 and 0.085 Å for Ho(III) and Pr(III), respectively, as well as to the values for Sparkle/PM3 of 0.064 and 0.093 Å for Gd(III) and Pr(III), respectively. Moreover, for all 15 lanthanide ions, these interatomic distance deviations follow a γ distribution within a 95% level of confidence, indicating that these errors appear to be random around a mean, freeing the model of systematic errors, at least within the validation set. Sparkle/PM6 presented here, therefore, broadens the range of applicability of PM6 to the coordination compounds of the rare earth metals.
authors.affiliation: Departamento de Química, Universidade Federal de Sergipe, 49.100-000, São Cristóvão, SE, Brazil and Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50.740-540, Recife, PE, Brazil.
authors.forename: Ricardo O
authors.initials: RO
authors.lastname: Freire
authors.affiliation: Departamento de Química, Universidade Federal de Sergipe, 49.100-000, São Cristóvão, SE, Brazil and Departamento de Química Fundamental, Universidade Federal de Pernambuco, 50.740-540, Recife, PE, Brazil.
authors.forename: Alfredo M
authors.initials: AM
authors.lastname: Simas