Computational estimation of lanthanoid-water bond lengths by semiempirical methods.

Over 650 lanthanoid complexes with Ln-OH(2) motifs have been modeled by the three semiempirical methods (AM1, PM3, or PM6)/SPARKLE. The geometrical deviations from the corresponding crystal structures can be described by normal distributions. Statistical inference analysis shows that AM1/SPARKLE is surprisingly accurate for the estimation of the average bond lengths Ln-OH(2) for the technologically important central lanthanoids (Ln = Eu-Tb) in complexes with pyridine-like ligands with a worst-case error of only 4.9%.